The boxer can only hit the tissue paper with a force as large as the tissue paper can exert on the boxer, and the low-mass tissue can only exert a weak force.
A boxer can hit a heavy bag with great force. Why can’t he hit a piece of tissue paper in midair with the same amount of force?
Moon pulls on Earth
The action is: Earth pull on Moon. What is the reaction?
Both pulls are the same.
Which force is greater, the Earth’s pull on the Moon, or the Moon’s pull on Earth?
The cannon has more mass than the shell.
If the cannon’s recoil is the result of an equal and opposite reaction, why is the cannon’s acceleration lower than the shell’s acceleration?
The action force doesn’t act on the same object as the reaction force.
Since movement of an object or system requires that a net force be applied to it, how can this occur if all action forces have opposite and equal reaction forces?
The force of friction the ground exerts on the horse is larger than the force the cart is pulling back on the horse.
A horse is pulling a cart. What allows the horse to accelerate forward even though the cart is pulling back on the horse?
There can never be only one force acting on an object.
Which of the following is NOT a statement or consequence of Newton’s third law?
All forces come in pairs
No force can exist on its own
There can never be only one force acting on an object.
Every force has an opposite and equal reaction
All forces come in pairs
No force can exist on its own
There can never be only one force acting on an object.
Every force has an opposite and equal reaction
the expelled gas pushing on the rocket
The force that propels a rocket is that provided by ______.
energetic reactions as the fuel is burned.
ejected fuel
the expelled gas pushing on the rocket
decreased mass.
energetic reactions as the fuel is burned.
ejected fuel
the expelled gas pushing on the rocket
decreased mass.
Friction between the apple and the floor
If an apple pulls on an orange, what is the force that accelerates the system across the floor.
pushes harder on the floor while holding the rope .
The team to win in a tug-of-war is the team that _______.
pulls with greater force
yanks the rope
has the greatest self confidence
pushes harder on the floor while holding the rope.
pulls with greater force
yanks the rope
has the greatest self confidence
pushes harder on the floor while holding the rope.
The net force is zero because the action and reaction forces are equal and opposite.
If the system is considered to be the apple and the orange together (apple and orange within the same system), is there a net force on the system when the apple pulls (ignoring friction with the floor)?
Yes, there must be an external net force on the system.
To produce a net force on a system, must there be an externally applied net force?
No, an internal net force is sufficient
No. To accelerate, the internal action forces must not equal the internal reaction forces.
Yes. To accelerate, the internal reaction forces must be zero.
Yes, there must be an external net force on the system.
No, an internal net force is sufficient
No. To accelerate, the internal action forces must not equal the internal reaction forces.
Yes. To accelerate, the internal reaction forces must be zero.
Yes, there must be an external net force on the system.
Both ropes are equally likely to break. (Since the attached rope doesn’t have to support any weight (as it did in the vertical case), the tension is the same in both ropes.)
A heavy crate is attached to the wall by a light rope. Another rope hangs off the opposite edge of the box. If you slowly increase the force on the free rope by pulling on it in a horizontal direction, which rope will break? Ignore friction and the mass of the ropes.
The magnitude of the force of the rifle is equal to the magnitude of force on the bullet and the forces are in the opposite direction, because for every action there is an equal and opposite reaction.
How does the force on the rifle compare with the force on the bullet, and why?
The acceleration of the rifle is smaller than the acceleration of the bullet. They experience the same magnitude of force, but the mass of the rifle is greater, and so the rifle will experience a smaller acceleration than the bullet.
How does the magnitude of acceleration of the rifle compare with the magnitude of acceleration of the bullet, and why?
The bullet will travel farther than the rifle because it has a greater magnitude of acceleration.
How does the distance traveled by the bullet compare with the distance traveled by the rifle in the same time, and why?
racquet
When hitting a tennis ball with your racquet, the force on the ball has the same magnitude as the force on the ______.
racquet, and in the same direction
racquet
player
hand that holds the racquet
racquet, and in the same direction
racquet
player
hand that holds the racquet
Yes, you pull up on Earth with the same force
Earth pulls down on you with a gravitational force that you call your weight. Do you pull up on Earth with the same amount of force?
Earth exerts a much greater force on you than you exert on Earth
No, the contact force from the ground cancels the force by you on Earth.
No, the contact force from the ground cancels the force of Earth on you.
Yes, you pull up on Earth with the same force.
Earth exerts a much greater force on you than you exert on Earth
No, the contact force from the ground cancels the force by you on Earth.
No, the contact force from the ground cancels the force of Earth on you.
Yes, you pull up on Earth with the same force.
Remember F=ma, and note that the cannon has a much greater mass than the cannon ball, so the cannon accelerates less for the same force.
If the forces that act on a cannonball and the recoiling cannon from which it is fired re equal in magnitude, why do the cannonball and cannon have very different accelerations?
The helicopter exerts downward forces on air; the reaction forces of the air on the helicopter are upward and called lift.
How does a helicopter get its lifting force?
The helicopter exerts downward forces on air; the reaction forces of the air on the helicopter are upward and called lift.
The helicopter exerts a downward force on Earth; the reaction force of Earth on the helicopter is called lift.
The helicopter exerts downward forces on the air that are slightly greater than the force of gravity, so it can hover.
The helicopter exerts upward forces on the air; the reaction forces of the air on the helicopter are downward and called lift.
The helicopter exerts downward forces on air; the reaction forces of the air on the helicopter are upward and called lift.
The helicopter exerts a downward force on Earth; the reaction force of Earth on the helicopter is called lift.
The helicopter exerts downward forces on the air that are slightly greater than the force of gravity, so it can hover.
The helicopter exerts upward forces on the air; the reaction forces of the air on the helicopter are downward and called lift.
5 N
A 7-N vector at an angle of 45* to the horizontal has a vertical component that is about _______.
3.5 N
5 N
7 N
0 N
3.5 N
5 N
7 N
0 N
magnitude of force
The length of a force vector indicates the _______.
inertia, acceleration, action-reaction
Fill in the blanks: Newton’s first law is often called the law of _______; Newton’s second law is the law of ______; and Newton’s third law is the law of _____.
a= 2.6 m/s^2
Forces of 2.0 N and 4.0 N act at right angles on a block of mass 1.7 kg.
Find the acceleration of the block
Find the acceleration of the block
F= 30N
If you stand next to a wall on a frictionless skateboard and push the wall with a force of 30 N, how hard does the wall push on you?
a= 0.35 m/s^2
If your mass is 86 kg, find your acceleration.
a= 450 m/s^2
A boxer punches a sheet of paper in midair and brings it from rest up to a speed of 20 m/s in 0.044s. What acceleration is imparted to the paper?
F=1.4 N
A boxer punches a sheet of paper in midair and brings it from rest up to a speed of 20 m/s in 0.044s. If the mass of the paper is 0.003 kg, what force does the boxer exert on it?
F= 1.4 N
A boxer punches a sheet of paper in midair and brings it from rest up to a speed of 20 m/s in 0.044s. How much force does the paper exert on the boxer?
A=B=C
Three identical pucks, A, B, and C, are sliding across ice at the given speeds. The forces of air and ice friction are negligible.
Puck A: 2m/s ->
Puck B: 4m/s –>
Puck C: 6m/s —>
Rank the pucks (from larges to smallest) by the force needed to keep them moving.
Puck A: 2m/s ->
Puck B: 4m/s –>
Puck C: 6m/s —>
Rank the pucks (from larges to smallest) by the force needed to keep them moving.
C, B, A
Three identical pucks, A, B, and C, are sliding across ice at the given speeds. The forces of air and ice friction are negligible.
Puck A: 2m/s ->
Puck B: 4m/s –>
Puck C: 6m/s —>
Rank the pucks (from larges to smallest) by the force needed to stop them in the same time interval.
Puck A: 2m/s ->
Puck B: 4m/s –>
Puck C: 6m/s —>
Rank the pucks (from larges to smallest) by the force needed to stop them in the same time interval.
The forces on each are the same in magnitude, and their masses are the same, so their accelerations will be the same. They will slide equal distances of 6 meters to meet at the midpoint.
Two people of equal mass attempt a tug-of-war with a 12m rope while standing on frictionless ice. When they pull on the rope, each of them slides toward the other. How do their accelerations compare, and how far does each person slide before they meet.
This cannot be done because both of them will pull with the same amount of force, and although their masses may differ, the amount of force that they pull from the scale will remain equal.
Your instructor challenges you and your friend to each pull on a pair of scales attached to the ends of a horizontal rope, in tug-of-war fashion, so that the readings on the scales will differ. Can this be done? Explain.
