# Physics Semester Exam

SI unit base unit used to measure mass
kilogram
What is the volume of a cube whose side is 10 m? (Volume = length x width x height)
1000 m^3
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Why do scientists use the metric system?
It’s easy to understand
Conversions are quite simple
The method of treating the units as algebraic quantities that can be cancelled is called dimensional analysis
True
How does a scientist reduce the frequency of human error and minimize a lack of accuracy?
All of the above:
take repeated measures
use the same method of measure
maintain instruments
The following students measure the density of a piece of lead three times. The density of lead is actually 8.9 g/cm3. Considering all of the results, which person’s results are both accurate and precise?
Lila: 8.89 g/cm3, 8.91 g/cm3, 8.92 g/cm3
Two laboratories use radiocarbon dating to measure the age of two wooden boat fragments found at the site of an ancient shipwreck. Lab A finds an age of 515 +/-20 years for the first object; lab B finds an age of 585 +/-30 years for the second object. Which of the following is true?
Lab B’s reading is less precise than Lab A’s.
A box has a length of 18 cm, a height of 19 cm, and a width of 20 cm. What is its volume?
6.84 x 10^3 cm3
A lack of precision in scientific measurements typically arises from
Limitations of the measuring instrument
What are some common mathematical relationships encountered in Physics?
Graphs often permit scientists to make estimations for times when there is no data.
True
A model that is created by replacing an object in motion with a series of single points is called a
particle model
Which of the following statements would be true about the particle model motion diagram for an airplane taking off from an airport?
The dots would be close together to start with, and get farther apart as the plane accelerated.
When dots are further apart on a ticker-tape diagram, it indicates an object is moving ______.
Fast
When dots on a ticker-tape diagram become closer together moving left to right, the object is _________.
Decelerating
In a motion diagram, the size of the object must be less than the distance moved.
False
Which of the following statements are TRUE when the spaces on a ticker-tape diagram do not change?
the object is not accelerating
the object has a constant speed
Internal motions within the object are used in creating a particle model.
False
Motion diagrams are used to show the location of a non-moving object over specific time intervals.
False
Movement that occurs along a straight line
Linear Movement
An object’s location and the time it takes to move to that location are the two observations used to create a motion diagram.
True
Time interval is a scalar quantity
True
It takes you 5 min to walk with an average velocity of .75 m/s to the north from the parking lot to the entrance of the amusement park. What is your displacement?
225 m to the north
A cyclist maintains a constant velocity of +7.0 m/s. At time t=0.0 s, the cyclist is +150 m from point A.The cyclist is moving away from point A. What is the cyclist’s position from point A at 45.0 s?
465 m
What is the resultant of two displacement vectors having the same direction?
The resultant is the sum of the two displacements having the same direction as the original vectors.
A vector diagram is needed to solve all physics problems properly.
FALSE
In a chosen coordinate system, the position of an object in motion can have negative values
True
A hiker hikes in a straight line and maintains a constant velocity of +0.5 m/s. At time t=0.0 s, the hiker is 30 m from point A. What is the displacement from point A at 120 s?
90 m
Heather and Matthew walk with an average velocity of .75 m/s eastward. If it takes them 25 min to walk to the park, their displacement must be 2.0 km to the east.
False
Which of the following statements is TRUE about a position versus time graph that illustrates changing velocity?
It is indicating some type of acceleration
The position-time graph of an object moving with a constant average velocity is always a straight line.
True
Which of the following is true about the position versus time graph of an object that comes to a stop, then remains at rest?
The slope changes to 0
When velocity is constant on a position versus time graph, the slope of the line is _________, but when velocity is changing over time, the slope is __________.
Constant
Changing
Average speed and average velocity are always the same.
False
__________ is displacement over time, while ____________ is velocity of an object at a single point
Average velocity
Instantaneous velocity
The slope of a position-time graph of an object gives the speed of the object
False
One runner in a relay race has a 1.50 s lead and is running at a constant speed of 3.25 m/s. The runner has 30.0 m to run before reaching the end of the track. A second runner moves in the same direction as the leader. What constant speed must the second runner maintain in order to catch up to the leader at the end of the race?
3.9 m/s
A swimmer travels from the south end to the north end of a 30.0 m pool in 15.0 s and makes the return trip to the starting position in 19.0 s. What is the average velocity for the second half of the swim?
1.6 m/s to the south
Four sheep are traveling the 250 m distance from the pasture back to the barn. After 45 seconds, their distances from the barn are as follows: Dolly – 170 m, Fluffy – 115 m, Ellie – 90 m, Ma – 200 m. According to average velocity, how would the sheep rank from slowest to fastest?
Ma, Dolly, Fluffy, Ellie
A fish swims 12.0 m in 5.0 s. It swims the first 4.0 m in 2.0 s, the next 3.0 m in 1.2 s, and the last 5.0 m in 1.8 s. What is the average velocity of the fish during the time interval between 0.0 s and 3.2 s?
2.2 m/s
When the line on a velocity versus time diagram moves away from the x-axis, the object is ________, but when the line moves toward the x-axis, the object is _____________
speeding up
slowing down
A comet experiences uniform acceleration from 60 m/s to 183 m/s in 10.0 s. What is its rate of acceleration?
12.3 m/s2
If an object is slowing down, its acceleration is in the ___________ direction of its motion, and if it is speeding up, its acceleration is in the _________ direction
Opposite
same
If a race car’s velocity increases from 4 m/s to 36 m/s over a 4 s time interval, its average acceleration would be 10 m/s2.
False
Which of the following is the equation for average velocity?
V avg = (Change in x) / (change in time)
Which of the following line segments on a position versus time graph is physically impossible?
A vertical line
Which of the following line segments on a velocity versus time graph is physically impossible?
Straight line with positive slope
Which of the following is the equation for acceleration?
a = (change in v) / (change in t)
Which situation illustrates constant acceleration?
object in free fall
an object’s velocity is decreasing by the same amount every minute
When a car’s velocity is positive and its acceleration is negative, what is happening to the car’s motion?
The car slows down
If velocity and time are positive in the positive y and x directions of the xy coordinate plane respectively, a velocity versus time graph for an object in free fall is a _______ line with a _______ slope
Straight
negative
A painter accidentally drops a can of paint from a high scaffold. What will be the velocity of the can after 2.0 s?
-20 m/s
A stone that starts at rest free falls for 7.0 s. How far does the stone fall in this time?
-2.4 x 102 m
Which would hit the ground first if dropped from the same height in a vacuum—a feather or a metal bolt?
They would hit the ground at the same time
A volleyball is dropped from a cliff and a soccer ball is thrown upward from the same position. When each ball reaches the ground at the bottom of the cliff, the volleyball will hit the ground with greater velocity
False
Which statement is TRUE about the velocity versus time graph of an object in free fall?
It starts from rest and ends with a large negative velocity
the graph is representative of constant acceleration
Two students are standing on a fire escape, one twice as high as the other. Simultaneously, each drops a ball. If the first ball strikes the ground at time Dt1 when will the second ball strike the ground? (Disregard air resistance. Assume a = -g = -9.81
Dt2 = (square root of 2) Dt1
Displacement is a vector quantity
True
Which statement is TRUE about vector quantity displacement?
It can be zero
Multiplying or dividing vectors by scalars results in
Vectors
Identify the following quantities as scalar or vector: the speed of a snail, the time it takes to run a mile, the free-fall acceleration.
scalar, scalar, vector
Instantaneous velocity is a scalar quantity
False
Which of the following is a physical quantity that has both magnitude and direction?
Vector
For the winter, a duck flies 10.0 m/s due south against a gust of wind with a speed of 2.5 m/s. What is the resultant velocity of the duck?
7.5 m/s south
Which of the following is an example of a vector quantity?
velocity
A football player runs in one direction to catch a pass, then turns and runs twice as fast in the opposite direction toward the goal line. Which of the following is a correct expression for the original velocity and the resulting velocity?
vplayer, -2vplayer
In a coordinate system, a vector is oriented at angle q with respect to the x-axis. The x component of the vector equals the vector’s magnitude multiplied by which trigonometric function?
cos q
In a coordinate system, a vector is oriented at angle q with respect to the x-axis. The y component of the vector equals the vector’s magnitude multiplied by which trigonometric function?
sin q
A duck waddles 2.5 m east and 6.0 m north. What are the magnitude and direction of the duck’s displacement with respect to its original position?
6.5 m at 67 north of east
What is the Pythagorean Theorem used to find and what must you have to use it?
magnitude
right triangle
If a cat moves from a negative position to a positive position, the cat’s displacement is:
positive
Which of the following exhibits parabolic motion?
a stone thrown into a lake
The downward force of gravity causes _______ displacement of an object, but the force of gravity does not affect the ________ component of motion.
negative
horizontal
Which of the following is the motion of objects moving in two dimensions under the influence of gravity?
projectile motion
What is the path of a projectile (in the absence of friction)?
a parabola
Which of the following is an example of projectile motion?
a thrown baseball
A projectile is any object which, once projected, continues its motion by ________, and is influenced only by the downward force of __________.
inertia
gravity
A cat chases a mouse across a 1.0 m high table. The mouse steps out of the way, and the cat slides off the table and strikes the floor 2.2 m from the edge of the table. When the cat slid off of the table, what was its speed?
4.9 m/s
Which of the following does not exhibit parabolic motion?
a flat piece of paper released from a window
Rafi is pulling a toy wagon through the neighborhood at a speed of 0.75 m/s. A caterpillar in the wagon is crawling toward the rear of the wagon at a rate of 2.0 cm/s. What is the caterpillar’s velocity relative to the ground?
.73 m/s
A piece of chalk is dropped by a teacher walking at a speed of 1.5 m/s. From the teacher’s perspective, the chalk appears to fall
straight down
Imagine that you are sitting in a car tossing a ball straight up into the air. If the car is moving at a constant velocity, will the ball land in front of, behind, or in your hand?
Which of the following is a coordinate system for specifying the precise location of objects in space?
frame of reference
A powerboat heads due northwest at 13 m/s relative to the water across a river that flows due north at 5.0 m/s. What is the velocity (both magnitude and direction) of the motorboat relative to the shore?
17 m/s, 33 west of north
Odina and LaToya are sitting by a river and decide to have a race. Odina will run down the shore to a dock 1.5 km away, then turn around and run back. LaToya will also race to the dock and back, but she will row a boat in the river, which has a current of 2.0 m/s. If Odina’s running speed is equal to LaToya’s rowing speed in still water, which is 4.0 m/s, who will win the race? Assume that they both turn instantaneously.
Odina will win the race
A girl at an airport rolls a ball north on a moving walkway that moves east. If the ball’s speed with respect to the walkway is 0.15 m/s and the walkway moves at a speed of 1.50 m/s, what is the velocity of the ball relative to the ground?
1.51 m/s 5.7 north of east
You are serving as a technical consultant for a locally produced cartoon. In one episode, two criminals, Shifty and Lefty, have stolen some jewels. Lefty has the jewels when the police start to chase him, and he runs to the top of a 60.0-m tall building in his attempt to escape. Meanwhile, Shifty runs to the convenient hot-air balloon 20.0 m from the base of the building and untethers it, so it begins to rise at a constant speed. Lefty tosses the bag of jewels horizontally with a speed of 7.3 m/s just as the balloon begins its ascent. What must the velocity of the balloon be for Shifty to easily catch the bag?
8.5 m/s
Which of the following forces arises from direct physical contact between two objects?
contact force
What causes a moving object to change direction?
force
A newton is equivalent to which of the following quantities?
kg x m/s2
A free-body diagram of a ball falling in the presence of air resistance would show
a downward arrow to represent the force due to gravity and an upward arrow to represent the force of air resistance.
The length of a force vector represents the
magnitude of the force
Which of the following statements does not describe force?
forces cause objects at rest to remain stationary
A free-body diagram represents all of the following except
forces exerted by the object
A car goes forward along a level road at constant velocity. The additional force needed to bring the car into equilibrium is
zero
Which situation illustrates Newton’s first law?
All of the above
What is true of the velocity versus time graph of an object receiving an applied net force?
It will be a line with either a positive or a negative slope.
A single force acts on an object. The components of this force act along the +x-axis and the -y-axis. The single force that will bring the object into equilibrium has components that act along the
-x-axis and +y-axis.
Which of the following is the tendency of an object to maintain its state of motion
inertia
A late traveler rushes to catch a plane, pulling a suitcase with a force directed 30.0° above the horizontal. If the horizontal component of the force on the suitcase is 60.6 N, what is the force exerted on the handle?
70 N
A waitperson carrying a tray with a platter on it tips the tray at an angle of 12° below the horizontal. If the gravitational force on the platter is 5.0 N, what is the magnitude of the force parallel to the tray that tends to cause the platter to slide down the tray? (Disregard friction.)
1 N
Which situation shows unbalanced forces acting on an object?
a book sliding on a table top
A ball is dropped from a person’s hand and falls to Earth. Identify an action-reaction pair in this situation.
Earth exerts a force on the ball; the ball exerts a force on Earth
Which action-reaction force pair is correct for a car moving along a road?
The force of the wheels on the road and the force of the road on the wheels
An airplane with a mass of 1.20 ´ kg tows a glider with a mass of 0.60 ´ kg. If the airplane propellers provide a net forward thrust of 3.60 ´ N, what is the acceleration of the glider? (Disregard friction.)
2 m/s2
A hammer drives a nail into a piece of wood. Identify an action-reaction pair in this situation.
The hammer exerts a force on the nail; the nail exerts a force on the hammer.
The statement by Newton that for every action there is an equal but opposite reaction is which of his laws of motion?
third
In general, Fnet equals
Sigma F
A hockey stick hits a puck on the ice. Identify an action-reaction pair in this situation.
The stick exerts a force on the puck; the puck exerts a force on the stick
There are six books in a stack, and each book weighs 5 N. The coefficient of static friction between the books is 0.2. With what horizontal force must one push to start sliding the top five books off the bottom one?
5 N
Mass is the magnitude of the force due to gravity acting on an object.
False
A change in the gravitational force acting on an object will affect the object’s
Weight
What are the units of the coefficient of friction?
The coefficient of friction has no units
A measure of the quantity of matter is
mass
The magnitude of the gravitational force acting on an object is
weight
A waitperson pushes the bottom of a glass tumbler full of water across a tabletop at constant speed. The tumbler and its contents have a mass of 0.70 kg, and the coefficient of kinetic friction for the surfaces in contact is 0.41. What force does the waitperson exert on the glass?
2.8 N
A sled weighing 1.0 ´ N is held in place on a frictionless 20.0° slope by a rope attached to a stake at the top. The rope is parallel to the slope. What is the normal force of the slope acting on the sled?
94 N
Work is done when
the displacement is not zero
A horizontal force of 200 N is applied to move a 55 kg television set across a 10 m level surface. What is the work done by the 200 N force on the television set?
2200 J
A worker does 25 J of work lifting a bucket, then sets the bucket back down in the same place. What is the total net work done on the bucket?
0 J
A construction worker pushes a wheelbarrow 5.0 m with a horizontal force of 50.0 N. How much work is done by the worker on the wheelbarrow?
250 J
A force does work on an object if a component of the force
is parallel to the displacement of the object
Which forces can do work on an object?
frictional force
applied force
If the sign of work is negative,
the displacement is in the direction opposite the force
The two SI units for work are newton-meters (N·m) and joules (J)
True
What forces act on the cars of a roller coaster when they enters loops and turns after reaching the initial summit?
all of the above
If friction is the only force acting on an object during a given physical process, which of the following assumptions can be made in regard to the object’s kinetic energy?
the kinetic energy decreases
How much elastic potential energy is stored in a bungee cord with a spring constant of 10.0 N/m when the cord is stretched 2.00 m?
20 J
What is the kinetic energy of a 0.135 kg baseball thrown at 40.0 m/s?
108 J
The main difference between kinetic energy and potential energy is that
kinetic energy involves motion, and potential energy involves position.
The equation for determining gravitational potential energy is PEg = mgh. Which factor(s) in this equation is (are) not intrinsic to an object?
g and h
An __________ force is a force that changes the mechanical energy of an object, for example, ________
external
friction
Gravitational potential energy is always measured in relation to
a zero level
Which of the following refers to the sum of kinetic energy and all forms of potential energy?
mechanical energy
Which of the following is a true statement about the conservation of energy?
total energy is always conserved
Which of the following is a form of mechanical energy?
gravitational potential energy
Why doesn’t the principle of mechanical energy conservation hold in situations when frictional forces are present?
KE is not completely converted to a form of PE
A 3.00 kg toy falls from a height of 1.00 m. What will the kinetic energy of the toy be just before the toy hits the ground?
29.4 J
A pendulum is raised 1.5 cm and allowed to fall. If air resistance is negligible, how high will the pendulum rise on the other side?
Exactly 1.5 cm
In the presence of frictional force,
nonmechanical energy is no longer negligible and mechanical energy is no longer conserved
Which of the following equations describes the relationship between work, power, and time?
P = w/t
A piano that weighs 575 N is lifted 20.0 m straight up by a rope attached to a motor-driven winch. It takes 10.0 s for the piano to reach this height. What power is developed by the motor in kW?
1.15 kW
Which of the following is the rate at which energy is transferred?
Power
A truck with a mass of 1.5 x 10^3 kg accelerates to a speed of 18.0 m/s in 12.0 s from a dead stop. Assume that the force of resistance is a constant 400.0 N during the acceleration. What is the average power developed by the truck’s engine?
2.38 x 10^4 W
What characteristics does a powerful lineman on a football team have?
can apply a large force and has a large velocity
Which of the following are not units of power?
J
What is one kilowatt-hour equivalent to?
3.6 x 10^6 J
Which of the following is the rate at which work is done?
power
How much power is required to lift a 2.0 kg mass at a speed of 2.0 m/s?
39 W
Which of the following equations is not an equation for power, P, in terms of work, W, displacement, d, time interval, force, F, and/or velocity, v?
p = (Fv) / (change in t)
A hard drive on a modern computer spins at 7200 rpm (revolutions per minute). If the drive is designed to start from rest and reach operating speed in 1.5 s, then the angular acceleration of the disk must be 2.0 x 103 rad/s2
False
A gear spins at 1880 rev/min. What is the angular displacement of the gear in 2.50s?
What will happen to angular frequency if there is a decrease in angular velocity?
angular frequency will decrease
What is the angular displacement of the second hand on a clock after 59 seconds?
__________ acceleration is the change in angular velocity over the change in time
angular
You replace the tires on your car with tires that have a larger diameter. After you change the tires, for trips at the same speed and over the same distance, the angular velocity and number of revolutions will both increase.
false
Joe is standing on the pedal of a bicycle. If his mass of 65 kg, the pedal makes an angle of 55º above the horizontal, and the pedal is 18 cm from the center of the chain ring, how much torque does he exert?
94 Nm
A bicycle-chain wheel with a radius of 7.70 cm is attached to a chain that exerts a 35.0-N force on the wheel in the clockwise direction. What torque would be needed to keep the wheel from turning?
+2.7 Nm
For everything that rotates, there is a specific moment of inertia for that object and for that specific axis of rotation. How can a figure skater decrease the moment of inertia while performing a spin?
pull arms in
A solid wooden wheel accelerates at 3.25 rad/s2 when a force of 4.5 N exerts a torque on it. If this wheel is replaced by a wheel with all of its mass on the rim, the moment of inertia is given by I = mr2. If the same angular velocity were desired, what force would have to be exerted on the wheel?
9 N
Two boxes are placed at opposite ends of a 3.0 m long board. The board is supported underneath by a fulcrum. The box on the left has a mass of 25kg, and the box on the right has a mass of 15 kg. Ignoring the mass of the board, where should the fulcrum be positioned under the board in order to balance the masses horizontally?
1.1 m from the left
Sam must perform a job that requires a torque of 32.4 N·m. He must use a 0.234-m-long wrench and exert a force of 232 N. What is the smallest angle, with respect to the vertical, that Sam needs to exert this amount of force?
36.6
A bolt is to be tightened with a torque of 8.0 N·m. If you have a wrench that is 0.35 m long, you must exert at least 33 N of force to tighten the bolt.
False
A wooden beam is 6.50 m long and weighs 325 N. It rests on two supports that are 3.00 m apart. Jane weighs 575 N. She stands on the beam in the center and then walks toward one end. How close to the end can she come before the beam begins to tip?
.848 m
A rubber ball moving at a speed of 5 m/s hit a flat wall and returned to the thrower at 5 m/s. The magnitude of the momentum of the rubber ball
remained the same
Which of the following equations can be used to directly calculate an object’s momentum, p?
p = mv
A person sitting in a chair with wheels stands up, causing the chair to roll backward across the floor. The momentum of the chair
was zero while stationary and increased when the person stood
Which type of collision is the most realistic?
partly elastic
Which of the following situations is an example of a significant change in momentum?
a tennis ball is hit into a net
What are the SI units for momentum?
kg x m/s
A roller coaster climbs up a hill at 4 m/s and then zips down the hill at 30 m/s. The momentum of the roller coaster
is greater down the hill than up the hill
Which of the following statements properly relates the variables in the equation FDt = Dp?
a large constant force acting over a long time interval causes a large change in momentum
A soccer ball collides with another soccer ball at rest. The total momentum of the balls
remains constant
A 0.75 kg model car is moving west at a speed of 9.0 m/s when it collides head-on with a 2.00 kg model truck that is traveling east at a speed of 10.0 m/s. After the collision, the 0.75 kg model car is now moving east at 11 m/s. What is the speed and direction of the model truck after the collision?
2.5 m west
The law of conservation of momentum states that
the total momentum of all objects interacting with one another remains constant regardless of the nature of the forces between the objects
In a two-body collision,
momentum is always conserved
The equation for the conservation of momentum in a two-body system is m1v1,i + m2v2,i = m1v1,f + m2v2,f.
True
Which statement is true about collisions
Upon collision, two moving objects experience a change in their accelerations
Two swimmers relax close together on air mattresses in a pool. One swimmer’s mass is 48 kg, and the other’s mass is 55 kg. If the swimmers push away from each other
their momenta are equal but opposite
A 0.105-kg soccer ball moving at 24 m/s is caught and held by a 75-kg goalie at rest. With what speed does the goalie fly backward?
.034 m/s
Which of the following statements about the conservation of momentum is not correct?
momentum is not conserved for a system of objects in a head on collision
A diver with a mass of 80.0 kg jumps from a dock into a 130.0 kg boat at rest on the west side of the dock. If the velocity of the diver in the air is 4.10 m/s to the west, what is the final velocity of the diver after landing in the boat?
1.56 m/s to the west
A child rides a bicycle in a circular path with a radius of 2.0 m. The tangential speed of the bicycle is 2.0 m/s. The combined mass of the bicycle and the child is 43 kg.
What is the magnitude of the bicycle’s centripetal acceleration?
2 m/s2
A car on a roller coaster loaded with passengers has a mass of 2.0 ´ kg. At the lowest point of the track, the radius of curvature of the track is 24 m and the roller car has a tangential speed of 17 m/s.

What centripetal force is exerted on the roller car at the lowest point?

2.4 x 10^4 N
The centripetal force on an object in circular motion is
in the same direction as the centripetal acceleration
When an object is moving with uniform circular motion, the object’s tangential speed
is constant
A child rides a bicycle in a circular path with a radius of 2.0 m. The tangential speed of the bicycle is 2.0 m/s. The combined mass of the bicycle and the child is 43 kg.
What is the magnitude of the centripetal force on the bicycle?
86 N
Which of the following can be a centripetal force?
all of the above
When an object is moving with uniform circular motion, the centripetal acceleration of the object
is directed toward the center of motion
Which situation shows centripetal acceleration?
both a and b
What is the term for the net force directed toward the center of an object’s circular path?
centripetal force
Which planets have the largest accelerations of gravity?
Jupiter, Neptune, Saturn
Which of the following equations expresses Newton’s law of universal gravitation?
Fg = G ((m1m2) / r2)
Gravitational force depends on __________ and __________
mass
distance
A planet has a mass of about 6.4 x 1023 kg, and its moon has a mass of about 9.6 x 1015 kg. If the magnitude of the gravitational force between the two bodies is 4.6 x 1015 N, how far apart are the planet and its moon?
9.4 x 10^6
A planet has a mass of 5.97 x 1024 kg and a radius of 6.38 x 106 m. Find the weight of a 65.0 kg person at 1000 km above the surface of this planet.
475 N
If you lift an apple from the ground to some point above the ground, the gravitational potential energy in the system increases. This potential energy is stored in
the gravitational field between Earth and the apple
Tides are caused by
differences in the gravitational force of the moon at different points on Earth.
A heavy bank-vault door is opened by the application of a force of 3.0 ´ N directed perpendicular to the plane of the door at a distance of 0.80 m from the hinges. What is the torque?
240 Nm
What causes a pulley system to be inefficient?
friction
If you want to open a swinging door with the least amount of force, where should you push on the door?
as far from the hinges as possible
If weights in a pulley system stay the same, but number of pulleys increases, applied force needed to lift the weight ___________
decreases
What is the efficiency of a machine that requires 1.00 ´ J of input energy to do 35 J of work?
35 %
If the torque required to loosen a nut on a wheel has a magnitude of 40.0 N·m and the force exerted by a mechanic is 133 N, how far from the nut must the mechanic apply the force?
30.1 cm
An iron bar is used to lift a slab of cement. The force applied to lift the slab is 4.0 ´ N. If the slab weighs 6400 N, what is the mechanical advantage of the bar?
16
Where should a force be applied on a lever arm to produce the most torque?
farthest from the axis of rotation
The higher the __________ of the pulley system, the __________ it is to lift the object
easier
How does a liquid differ from a gas?
a liquid has definite volume, unlike a gas
A buoyant force acts in the opposite direction of gravity. According to Archimedes’ Principle, which of the following is true of an object completely submerged in water?
The magnitude of the upward buoyant force on the object is equal to the weight of the fluid displaced by the object
According to legend, to determine whether the king’s crown was made of pure gold, Archimedes measured the crown’s volume by determining how much water it displaced. The density of gold is 19.3 g/cm. If the crown’s mass was 6.00 ´ g, what volume of water would have been displaced if the crown was indeed made of pure gold?
31.1 cm3
A cube of wood with a density of 0.780 g/cm is 10.0 cm on each side. When the cube is placed in water, what buoyant force acts on the wood?
7.65 N
For incompressible fluids, density changes little with changes in
pressure
How does a submarine use its tanks to float and sink?
When on the surface of the water the tanks are filled with air, and in order to sink the tanks fill with water
When a gas is transferred from one container into another container, which of the following does not occur?
the gas keeps its original volume
Which of the following is a fluid?
helium
Density determines whether an object sinks or floats.
true
Which of the following is true about how pressure varies with depth in a fluid?
Pressure increases with depth because it must support the fluid weight above it.
What factors affect the gauge pressure within a fluid?
fluid density, depth, free fall acceleration
If the air pressure in a tire is measured as 2.0 ´ Pa, and atmospheric pressure equals 1.0 ´ Pa, what is the absolute pressure of the air inside the tires?
3 x 10^5 Pa
A car has four tires that are each inflated to an absolute pressure of 2.0 x 105 Pa. Each tire has an area of 0.024 m2 in contact with the ground. How much does the car weigh?
1.9 x 10^4 N
A water bed weighs 1025 N, and is 1.5 m wide by 2.5 m long. How much pressure does the water bed exert if the entire lower surface of the bed makes contact with the floor?
2.7 x 10^2
The gauge pressure for the air in a balloon equals 1.01 ´ Pa. If atmospheric pressure is equal to 1.01 ´ 10656-10-02-00-00_files/i0110001.jpg Pa, what is the absolute pressure of the air inside the balloon?
2.02 x 10^5
A water bed that is 1.5 m wide and 2.5 m long weighs 1055 N. Assuming the entire lower surface of the bed is in contact with the floor, what is the pressure the bed exerts on the floor?
280 Pa
Which of the following statements is always true?
Pressure always increases when force increases or the area acted on decreases.
Which of the following is not an example of turbulent flow?
a river flowing slowly in a straight line
Which of the following properties is not characteristic of an ideal fluid?
turbulent flow
Bernoulli’s principle relates to racecars because
as the velocity of a race car increases, the pressure exerted by the race car’s wheels decreases, keeping the wheels on the ground
A 0.250 m diameter natural-gas pipeline delivers 1.55 m3 of gas per second. What is the gas’ flow speed through the pipeline?
31.6 m/s
A faucet tap with a diameter of 2.0 cm fills a 2.5 x 10-2 m3 container in 30.0 s. What is the speed of the water flow?
2.7 m/s
What happens when a person blows between two paper cups that are hung by strings 10 cm apart?
the cups move toward each other
If the flow rate of a liquid is measured at 8.0 ´ going through a 20.0 m radius pipe, which of the following is the average fluid velocity in the pipe?
6.4 m/s
Water has a pressure of 3.00 x 105 Pa and a speed of 1.00 m/s as it flows through a horizontal pipe. At a certain point, the pipe narrows to one-fourth its original diameter. (Remember the radius is half of the diameter, so its radius will also be one-fourth its original size.) What is the speed of the water flow in the narrow section of the pipe?
16 m/s
A water tunnel has a circular cross section where the diameter diminishes from 3.6 m to 1.2 m. If the velocity of water is 3.0 m/s in the larger part of the tunnel, what is the velocity of water in the smaller part of the tunnel?
27 m/s
Gases, liquids, and solids of the same substance with equal masses all have the same amount of thermal energy
False
Which of the following is a direct cause of a substance’s temperature increase?
kinetic energy is added to the particles of the substance
As the temperature of a substance increases, its volume tends to increase due to
thermal expansion
What is the temperature of a system in thermal equilibrium with another system made up of ice and water at 1 atm of pressure?
273 K
When a closed tin is heated, the pressure inside it increases. This happens because:
the molecules move faster and each molecule strikes the walls of the tin more often
Which of the following is proportional to the kinetic energy of atoms and molecules?
temperature
Which of the following best describes the relationship between two systems in thermal equilibrium?
no net energy is exchanged
The temperature of a system must increase when heat energy is added.
false
The entropy of an isolated system never decreases.
true
Why isn’t there a change in temperature during a phase change?
The energy would be used by the increasing motion of molecules
According to the First Law of Thermodynamics, the change in thermal energy of an object is equal to the heat added to the object divided by the work done by the object.
false
If you are able to see an object, how can you be sure that it is not at absolute zero
As soon as light hits the object, it gives the object energy and it will no longer be at absolute zero
The entropy of a system measures the state of disorder of the system
true
50 g of ice at 0°C is dropped in a beaker containing 100 g of water at 0°C. What will be the contents of the beaker after 5 hours? Assume that the room temperature is 0°C.
50 g of ice and 100 g of water

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