# SCIENCE - Chapter 3

b. newton
The metric unit of force preferred by scientists is the:
a. kilogram.
b. newton.
c. mima.
d. pound.
b. gravity
Weight is a force that depends on mass and:
a. friction.
b. gravity.
c. magnetism.
d. energy conservation
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b. Friction
Which of the following forces is a contact force?
a. Gravity
b. Friction
c. Magnetism
d. Electricity
c. Pound
Which of the following is the largest unit of force?
a. Kilogram
b. Ounce
c. Pound
d. Newton
c. 19,600 N
If an elephant has a mass of 2,000 kg, what is her weight on Earth? a. 0.0049 N
b. 204 N
c. 19,600 N
d. 43,100 N
d. Force
Of the following measurements, the one that would be incomplete without giving a direction is:
a. time.
b. temperature.
c. length.
d. force.
d. 7.0 N
On a vector drawing, Alexi decides to use a scale of 1.0 cm = 2.0 N. The force represented by an arrow 3.5 cm long would be:
a. 1.0 N
b. 2.0 N
c. 3.5 N
d. 7.0 N
b. your weight would be less but your mass would remain the same.
Compared to your weight and mass on Earth, if you were on the moon:
a. your weight and mass would be less.
b. your weight would be less but your mass would remain the same.
c. your weight would remain the same, but your mass would be less.
d. your weight would increase, but your mass would remain the same.
b. acceleration and force
Which pair of terms are vectors?
a. speed and mass
b. acceleration and force
c. velocity and speed
d. mass and weight
b. Sliding friction
A force that resists the motion of an object moving across a surface is called:
a. static friction.
b. sliding friction.
c. rolling friction.
d. air friction.
B. Air cushion
What does a maglev train use to reduce friction?
a. Oil
b. Air cushion
c. Ball bearings
d. Water
D. Friction
A force that resists motion is called:
a. weight.
b. motion.
c. equilibrium.
d. friction.
b. they replace sliding friction with rolling friction.
Ball bearings decrease friction in rotating motion because:
a. they are made of hard steel.
b. they replace sliding friction with rolling friction.
c. they separate surfaces with a cushion of air.
d. they can be made in all sizes to fit different machines.
a. Increasing the weight on your foot.
Which of the following would increase the sliding friction between your foot and the floor?
a. Increasing the weight on your foot.
b. Decreasing the weight on your foot.
c. Putting water between your foot and the floor.
d. Separating your foot and the floor
A. They increase friction.
The tires on a car have grooves in them. How do these grooves affect the friction between the tires and the road during wet weather?
a. They increase friction.
b. They decrease friction.
c. They have no effect on friction.
d. They first decrease, then increase friction.
c. By separating surfaces with a lubricant.
How can the force of friction between two surfaces be reduced?
a. By changing rolling friction to sliding friction.
b. By making smooth surfaces rougher.
c. By separating surfaces with a lubricant.
d. By increasing the force between the surfaces.
a. Heat and sound.
Which types of energy are released by the friction force between a car’s tires and the road during a skidding, squealing stop?
a. Heat and sound
b. Motion and friction
c. Nuclear and gravity
d. Lubrication and motion
d. the object will not change direction or speed.
If the net force on a moving object is zero:
a. the object will slow down and stop. b. the object will change direction.
c. the object will change speed.
d. the object will not change direction or speed.
True
True or false.
-Weight- is a force from gravity pulling down on any object with mass.
False, decrease
True or false.
By compressing a spring, you -increase – its length.
False, greater
True or false.
The greater the force squeezing 2 surfaces together, the -smaller- the friction force.
False, unbalanced
True or false.
A -zero- net force causes an acceleration.
True
True or false.
Force is the ability to change motion.
True
True or false.
Tension is a contact force.
Equal to
If you traveled to Mars, your mass would be _________________________ than your mass on Earth.
Pound
The _________________________ is the English unit of weight equal to about 0.454 kg of mass.
Friction
A force that resists the motion of objects or surfaces as they move over one another is called ____________________.
Free-body
A diagram shows all the forces acting on an object is a _________________________ diagram.
Vector
Force is a(n) ____________________ because it has both an amount and a direction.
Newton
The metric unit of force required for a 1-kg object to accelerate at 1 m/s2 is the _________________________.
Both are forces ; Friction is a contact force and gravity is an at-a-distance force.
Describe one similarity and one difference between friction and gravity.
Weight depends on gravity. The strength of gravity depends on the size of the planet.
Explain how the same object could weigh 50 pounds on Earth and 8.3 pounds on the moon.
Friction keeps you feet from slipping and allows you to walk foward
If there were no friction, we could not walk. Explain why friction is necessary for walking.
The forces are balanced and the objects are not accelerating
What does it mean when the net force on an object is zero?
132 N
A toddler weighs 30.0 pounds. If 1.00 newton equals the weight of 0.228 pounds, what is the weight of the toddler in units of newtons?
Ivan
Two body builders are involved in a weight lifting contest to determine who is the stronger. Ivan lifts 500 pounds. Vladimir lifts 2000 newtons. Who is stronger?
To start an object moving, static friction force must be overcome. To keep an object moving, sliding friction force must be overcome. For a given object, the value for the static friction force is greater than the sliding friction force.
When trying to slide an object, it is generally easier to keep the object moving than it is to start the object moving. Explain why this is so including the terms static and sliding friction in your explanation.
6.67
What does the “G” stand for in the law of universal gravitation equation?
Satellite that takes 24 hours to complete on revolution
Geocrynconized orbit
Triangulate your position to using three objects
What does it mean to triangulate your signal?
False
True or false.
All satellites are in geocyncronized orbit.
The goal momentum will not change unless from an outside force
Conservation Momentum
Kg x m/s
What is the unit for momentum?
M / s
What is the unit for velocity?
Newtons
What is the unit for net force, weight, and friction?
m/s^2
What is the unit for acceleration?
P = mv
What is the equation for collision?
false, momentum
True or false.
As a skateboard increases her speed (in velocity) from 2 m/s to 4m/s, she also increases her -inertia-.
false, 3rd law
True or false.
“For every action there is an equal and opposite reaction’ is a statement of Newton’s first law of motion.
true
True or false.
Units for measuring impulse, newton-seconds, are equivalent to kilogram-meters per second, units for measuring momentum.
third
Forces occur in pairs is another way of stating Newton’s _____ law of motion.
the rocket pushes on exhaust gases and the exhaust gases push back on the rocket
A rocket can fly into space because:
a. the exhaust gases push against the ground and the ground, in turn, pushes the rocket
b. the rocket pushes on exhaust gases and the exhaust gases push back on the rocket
c.as the fuel burn, the rocket’s mass decreases reducing the force of gravity on the rocket
d. the launch pads absorbs momentum that it imparts to the rocket
mass x velocity
What is the equation to calculate momentum?
a. increasing momentum
As the speed of a rolling ball is increasing the increasing speed is accompanied by
a. increasing momentum
b. increasing inertia
c. decreasing momentum
d. both increasing inertia and momentum
c. momentum
The impulse applied to an object is equal to the change in the objects
a. mass
b. inertia
c. momentum
d. height
d. all of the above
To increases the final momentum of a racquetball, the player should:
a. swing the racquet as fast as possible
b. follow through when hitting the ball
c. increase contact time with the ball
d. all of the above
d. 40,000 kg x m/sec.
The momentum of a 2000 kilogram car traveling at 20 meters per second is:
a. 0 kg x m/sec.
b. 0.001 kg x m/sec.
c. 100 kg x m/sec.
d. 40,000 kg x m/sec.
c. 7,500 m/sec.
If a 40,000 kilogram rocket were traveling from its launch pad at a speed of 150 meters per second, 800 kilograms of gases would be expelled from the rocket at a speed of about:
a. 0.33 m/sec.
b. 270 m/sec.
c. 7,500 m/sec.
d. 21,000 m/sec.
d. The directions of the ball’s momentum and Jolene’s momentum are the same.
While standing on a stationary skateboard, Jolene tosses a heavy ball horizontally toward one end of her skateboard. The skateboard moves. Assuming there is no friction in the system when the ball is tossed, which statement about the momentum of the heavy ball is INCORRECT?
a. The ball’s momentum is equal in size to the momentum of Jolene and her skateboard.
b. The ball’s momentum plus the momentum of Jolene and her skateboard equals zero.
c. The ball’s momentum has increased because Jolene has tossed it.
d. The directions of the ball’s momentum and Jolene’s momentum are the same.
c. gain in kinetic energy.
An object falls without friction near Earth’s surface. The loss of its potential energy is equal to its:
a. loss of height.
b. loss of mass.
c. gain in kinetic energy.
d. gain in velocity.
b. action and reaction forces are applied to different objects.
Even though every action force has an equal but opposite reaction force, they do not cancel one another and motion may still occur because the:
a. action and reaction forces are applied to the same object.
b. action and reaction forces are applied to different objects.
c. two forces have different magnitudes.
d. two forces have equal magnitudes.
a. Two billiard balls collide and bounce off each other.
Which of the following situations is an example of a mostly elastic collision?
a. Two billiard balls collide and bounce off each other.
b. Two train card collide and stick together.
c. When a soft piece of clay falls onto the floor, its shape flattens.
d. A glass falls off the table and breaks.
b. potential
Energy that is stored due to the position of an object may be called ____ energy.
a. kinetic
b. potential
d. nuclear
c. energy and is measure in joules
The ability to cause change is defined as:
a. force and is measured in newtons.
b. power and is measured in watts.
c. energy and is measured in joules.
d. impulse and is measured in newton-seconds.
b. The baseball is stopped with less force because it has less momentum.
A 0.15-kilogram baseball thrown at a speed of 50 meters per second and a 7.25-kilogram bowling ball rolling at 2 meters per second are both stopped in 0.2 seconds.
a. The baseball is stopped with less force because it has less inertia.
b. The baseball is stopped with less force because it has less momentum.
c. The bowling ball is stopped with less force because it has less momentum.
d. The bowling ball is stopped with less force because it has less inertia.
c. the time interval for stopping is greater when Kiki catches the glass with her foot.
Kiki accidentally nudges a glass tumbler with her elbow and it falls toward a hard, ceramic tile floor. As a soccer player, Kiki reacts by catching the glass with her foot and lowering it to the floor, preventing the glass from breaking. Her action prevents the breakage because:
a. the change in momentum is smaller when Kiki catches and lowers the glass to the floor.
b. the impulse is smaller when Kiki catches the glass and lowers it to the floor.
c. the time interval for stopping is greater when Kiki catches the glass with her foot.
d. a larger force is exerted by Kiki’s foot to stop the glass in time.
d. is larger than the force applied by the ground on the skateboard.
The skateboard on which you are standing moves as one of your feet pushes on the ground because the force you apply on the skateboard:
a. equals the force applied to you by the skateboard.
b. is larger than the force applied to you by the skateboard.
c. equals the force applied by the ground on the skateboard.
d. is larger than the force applied by the ground on the skateboard.
c. Halfway to the floor
A 20-kilogram object falls 2.0 meters to the floor. At what point in its fall does the kinetic energy of a body equal its potential energy?
a. At all points of the fall
b. Very nearly at the top of the fall
c. Halfway to the floor
d. Just the instant before it hits the floor
b. increases by four times.
As the speed of a moving object doubles, the amount of mechanical kinetic energy that it possesses:
a. increases by two times.
b. increases by four times.
c. decreases by two times.
d. decreases by four times.
d. force multiplied by the distance moved in the same direction as the force.
In science, work is defined as:
a. the mass of an object multiplied by its acceleration.
b. the mass of an object multiplied by the force required to move it.
c. force multiplied by the distance moved in a direction perpendicular to the force.
d. force multiplied by the distance moved in the same direction as the force.
d. all of the above
To increase the final momentum of a racquetball, the player should:
a. swing the racquet as fast as possible.
b. follow through when hitting the ball.
c. increase contact time with the ball.
d. All of the above
b. 15 joules
Calculate the work done to lift a barbell weighing 100 newtons a distance of 1.5 meters.
a. 0.015 joules
b. 15 joules
c. 66.7 joules
d. 150 joules
b. 2 m/sec
A 2-kilogram piece of clay moving at 4 m/sec strikes and sticks to a second 4-kilogram piece of clay moving at 1 m/sec in the opposite direction. Calculate the speed of the combined piece of clay.
a. 1 m/sec
b. 2 m/sec
c. 4 m/sec
d. 6 m/sec
d. zero loss of kinetic energy.
All of the following may be the result of an inelastic collision EXCEPT:
a. permanent change in the shape of the colliding bodies.
b. kinetic energy released as sound.
c. colliding bodies stick to one another.
d. zero loss of kinetic energy.
d. increasing the time of collision.
Air bags reduce injury in automobile accidents by:
a. reducing the time of collision.
b. reducing the change in momentum.
c. increasing the applied force.
d. increasing the time of collision.
d. 1,400 joules
Lifting a 70-kilogram barbell 2.0 meters above the floor increases its potential energy by about:
a. 35 joules.
b. 140 joules.
c. 350 joules.
d. 1,400 joules.
b. 4 m/sec
A boy whose mass is 40 kilograms runs at 5 meters per second and jumps onto a 10-kilogram stationary sled. The boy slides on the sled over a horizontal, frictionless surface at a speed of:
a. 2 m/sec.
b. 4 m/sec.
c. 5 m/sec.
d. 10 m/sec.
c. 0.78
The amount of mechanical kinetic energy possessed by a 0.25-kilogram ball rolling at a speed of 2.5 meters per second is ____ joules.
a. 0.31
b. 0.63
c. 0.78
d. 1.6
a. slows rolling up an incline
Potential energy increases as a marble:
a. slows rolling up an incline.
b. increases speed down an incline.
c. rolls at uniform speed on a level table.
d. sits motionless on the floor.
collision
When two objects hit each other a _______ occurs.
d. 14
Ken rolls a 7-kilogram bowling ball so slowly that it stops before it moves through all of the pins. The impulse necessary to stop this bowling ball rolling at 2 meters per second is ____ newton-seconds.
a. 3.5
b. 5.0
c. 7.0
d. 14
d. 10,000 newtons
What braking force is needed to stop a 1,000-kilogram car moving at 10 m/sec in a time of 1 seconds?
a. 1 newton
b. 10 newtons
c. 100 newtons
d. 10,000 newtons
momentum
As Maria steps from a small rowboat towards a pier, the boat moves away from the pier. Maria falls into the water. She is a “victim” of the law of conservation of ____________________.
kinetic
The expression 1/2 mv^2 represents ____________________ energy.
impulse
The expression f x t represents _________________________.
conservation of energy
“Energy can never be created or destroyed, just transformed from one form to another” is a statement of the law of ______________________________ (three words).
impulse
Alicia is asked to calculate the change in momentum that occurs as she stops her bicycle. This is equivalent to the ____________________ applied to the bicycle.
speed ; mass
The kinetic energy of an object depends upon two things: ____________________ and ____________________.
F
The expression mgh represents _________________________ energy.
a. 17 newton-seconds
Alex hits a line drive directly up the middle which leaves his bat traveling at 250 meters per second. If the pitcher has thrown the 0.15-kilogram baseball to Alex at 140 meters per second, what is the impulse applied to the baseball by Alex?
a. 17 newton-seconds
b. 21 newton-seconds
c. 38 newton-seconds
d. 50 newton-seconds
b. 30 newton-seconds
What impulse must be applied to a 3-kilogram object to give it 150 joules of kinetic energy?
a. 21 newton-seconds
b. 30 newton-seconds
c. 50 newton-seconds
d. 3,000 newton-seconds
b. trampoline applies a larger impules
Jumping on a tramp line, Jeffrey can easily soar 6 feet into the air but can only jump 2 feet from the blacktop of the driveway basketball court because the:
a. court applies a larger impulse
b. trampoline applies a larger impulse
c. court applies less force on Jeffrey
d. trampoline applies more force on Jeffrey
c. joules
Work may be measure using the units of?
a. watts
b. newtons
c. joules
d. newtons per second
b. 1.5 meters
Jonah is pushing his young sister, Jessica, on a swing. If Jessica weighs 350 newtons, how much higher above the ground must Jonah push her to increase her potential energy by 525 joules?
a. 0.67 meters
b. 1.5 meters
c. 3.6 meters
d. 5.4 meters
c. 0.78
The amount of kinetic energy possessed by a 0.25-kilogram ball rolling at a speed of 2.5 meters per second is ______ joules.
a. 0.31
b. 0.64
c. 0.78
d. 1.6
c. 9 times greater
When the brakes are fully applied, compares to the distance required to stop a car going 30 miles per hour, the distance needed to stop a car going 90 miles per hour is:
a. 3 times as great
b. 6 times as great
c. 9 times as great
d. the same
the forces are the same
A speeding truck makes contact with a bug on its windshield. Compare the force that the bug exerts on the truck to the force the truck exerts on the bug.
the forces are applied to different objects ; the force that causes motion is your feet on the ground, which is greater than the force the ground has on the wheels
When you push on your friend who is seated in a wagon, the wagon moves. According Newton’s 1st law of motion, the force you apply to your friend is equal but opposite to the force your friend applies to you. Explain why the two equal and opposite forces do not cancel one another with no resulting motion. tell what foes does cause the motion.
when athletes follow through, they have great speed and impulse, along with more momentum
As a tennis player, golfer, baseball player or soccer player yu might be told by your coach to “follow through” when stiking the ball. Explain why.
60 kg x m/s
Calculate the momentum of a 30-kilogram cart moving at a speed of 2.0 meters per second.
1.3 m/s
While sitting motionless on a 10-kilogram, friction-free wagon, 75-kilogram “Bozo, the human target” catches an 8-kilogram cannonball moving at 15 meters per second. After cathing the cannonball, at what speed do Bozo, the wagon and cannonball move?
900 kg x m/s
Calculate the size of the impulse that must be applied to stop a 200-kilogram wagon rolling on a flat path at a speed of 4.5 meters per second.
14.7 meters
Calculate the maximum height a 0.75-kg ball will rise if it is kicked straight up with an initial speed of 17 meters per second.
when someone walks forward or dry car tires
Give me an example of static friction.
car sliding (with wet tires) or when one is going down a hill
Give me an example of kinetic friction.
acceleration
Is a car moves at a constant velocity, the forces are balanced because there is no _________.
net force
____ ______ causes acceleration.

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