Question 1

The impulse required to bring an auto to a stop is ordinarily provided by __________________ forces.

Accepted Answer

The answer of The impulse required to bring an auto...

Question 2

A moving cue ball strikes another ball of equal mass that is initially at rest on the flat planar surface of the pool table. If the collision is elastic, the direction of the velocity of the cue ball after the collision will be __________________ to the direction of the velocity of the other ball.

Accepted Answer

The answer of A moving cue ball strikes another ball...

Question 3

A toy car and a toy truck at rest have a compressed spring in between them. The truck has more mass than the car. The spring is released and the two cars move in opposite directions. Which of the following is true?
A) The magnitude of the truck's momentum is the same as the car's.
B) The magnitude of the truck's momentum is larger than the car's.
C) The magnitude of the truck's momentum is smaller than the car's.
D) It is not possible to tell which has more momentum without knowing the speeds.

Accepted Answer

According to the law of conservation of momentum, the total momentum of a system remains constant if no external forces act on it. When the spring is released, the momentum transferred to the truck is equal in magnitude but opposite in direction to the momentum transferred to the car, making their momenta equal in magnitude.

Question 4

A force acts on an object for a time. If one eighth the force had acted for twice as long, the impulse would have been __________ as much as before.

Accepted Answer

The answer of A force acts on an object for...

Question 5

A robot spacecraft is sent to Mars to explore the Martian polar ice cap. Designers can surround it with a set of inflatable balloons that pop out like automobile air bags as soon as the spacecraft's re-entry parachute opens up.  When the spacecraft lands, it will be able to roll for a few meters across the surface of Mars. The popout balloons have an advantage to the spacecraft, because
A) they cancel out the normal force of the surface of Mars.
B) they decrease the kinetic energy.
C) they increase the time of impact and lessen the stopping force.
D) the impulse that stops the spacecraft for landing is less with these balloons.

Accepted Answer

The popout balloons increase the time of impact and lessen the stopping force when the spacecraft lands on Mars. This helps to reduce the damage and stress on the spacecraft during landing.

Question 6

If a single force acts on a moving object
A) the momentum of the object will change only if the force is in the same direction as the velocity of the object.
B) the momentum of the object must change.
C) the momentum of the object can only change magnitude, not direction.
D) the momentum of the object can only change direction, not magnitude.

Accepted Answer

According to the impulse-momentum theorem, a force acting on an object will cause a change in momentum of the object. Therefore, the momentum of the object must change when a force is applied to it, regardless of the direction of the force with respect to the object's velocity.

Question 7

A big defensive lineman picks up a fumbled football and begins rumbling toward the end zone. His mass is 150 kg, and his velocity is 6.0 m/s, west. A brave wide receiver, whose mass is 90 kg, must stop that lineman and he is right in the lineman's path, so it has to be a head-on collision. How fast must the wide receiver be running if he wants to drop the lineman in his tracks and save the day?
A) 88 mph
B) 0.60 m/s
C) 8.3 m/s
D) 10 m/s

Accepted Answer

The answer of A big defensive lineman picks up a...

Question 8

A rocket obeys the principles of recoil. However, it is much more difficult to apply Newton's second law to a rocket because
A) Newton's three laws do not apply in outer space.
B) there is actually sideways momentum, because a rocket motor is just a well-controlled explosion.
C) the rocket pushes against air but the air is a fluid.
D) as the rocket motor fires the total mass of the rocket changes.

Accepted Answer

Newton's second law states that force is equal to mass times acceleration. However, in the case of a rocket, the mass is constantly changing as fuel is burned up and expelled out of the rocket, making it difficult to calculate the exact acceleration and therefore the force being applied.

Question 9

A 60 kg boy standing on a skateboard with frictionless wheels and negligible mass throws a 3 kg ball straight up with a speed of 4 m/s. If the boy was at rest before the throw, his speed after the throw will be _________________.

Accepted Answer

The answer of A 60 kg boy standing on a...

Question 10

If the same impulse is applied to a ping-pong ball and a baseball, the change in the ping-pong ball's momentum will be _____________ the baseball's.

Accepted Answer

The answer of If the same impulse is applied to...

Question 11

An oil tanker heading due west, straight into a strong wind, reaches a speed of 5 m/s and then shuts down its engines to drift. The forward-facing flat surfaces of the tanker catch a total of 60,000 N of force from the wind. This wind force is pointing backwards, to the east. The tanker's mass is 100,000 metric tons, which is 100 million kg. If the wind blows at the same strength for 5 minutes, then how much has the wind changed the tanker's speed?
A) 1.2 m/s
B) 1.08 m/s
C) 0.018 m/s
D) 0.18 m/s

Accepted Answer

We can use the formula F = ma to find the acceleration experienced by the tanker due to the wind force.

F = ma
60,000 N = 100,000,000 kg * a
a = 0.0006 m/s^2

Next, we can use the kinematic equation v = u + at to find the change in speed of the tanker after 5 minutes of wind force.

u = 5 m/s (initial speed)
t = 5 minutes = 300 seconds
a = -0.0006 m/s^2 (negative because it is opposing the direction of motion)
v = u + at
v = 5 m/s - 0.0006 m/s^2 * 300 s
v = 4.82 m/s

Therefore, the wind has changed the tanker's speed by:

Δv = 5 m/s - 4.82 m/s = 0.18 m/s

Thus, the answer is D) 0.18 m/s.

Question 12

Two astronauts of equal mass are holding on to each other and moving at a speed of 30 m/s. They push off of each other and one of the astronauts moves in the same direction as the two were initially moving but at 60 m/s. The velocity of the second astronaut is
A) 60 m/s backward.
B) 30 m/s backward.
C) zero.
D) 30 m/s forward.
E) 60 m/s forward.

Accepted Answer

The answer of Two astronauts of equal mass are holding...

Question 13

If a bullet is fired into a wooden block and remains lodged in the block, the collision was _________________.

Accepted Answer

The answer of If a bullet is fired into a...

Question 14

The total momentum of a system will change during a collision unless the ____________ force is zero.

Accepted Answer

The answer of The total momentum of a system will...

Question 15

If heat, sound, or deformation of solid bodies results from a collision, there will be a change in the total ____________ __________.

Accepted Answer

The answer of If heat, sound, or deformation of solid...

Question 16

If you were standing on a cart that was at rest and free to roll (ignore friction) and someone threw a 10 kg ball at you, you would
A) not move if you caught the ball because you are more massive than the ball.
B) roll backward faster if you caught the ball.
C) roll backward faster if the ball bounced off of you elastically.
D) roll backward faster if you caught the ball higher above the ground.

Accepted Answer

According to the law of conservation of momentum, if the ball bounces off of you elastically, it will transfer its momentum to you and the cart, causing you to roll backward faster. This is because the momentum of the system (you, the cart, and the ball) must be conserved. If you caught the ball or caught it higher above the ground, the momentum transfer would be less, so you would not roll backward as fast.

Question 17

When a single boxcar in the freight yard hooks onto a stationary string of four boxcars, as in example 7.4, there is some kinetic energy lost. Which of the following could account for the missing energy?
A) Sound energy in the loud CLANG when they hook together.
B) Heat energy in the clamping mechanism between cars as it opens and then captures the fifth boxcar.
C) Both A and B

Accepted Answer

The missing energy during the collision can be accounted for by both sound energy produced by the loud clang and heat energy generated in the clamping mechanism as it operates to connect the cars.

Question 18

If a bullet is fired into a solid wooden block and comes out the other side, the collision was _________________ inelastic.

Accepted Answer

The answer of If a bullet is fired into a...

Question 19

Consider a system containing three objects that move with different velocities. The objects can interact with each other through forces. In this system
A) the total kinetic energy of the objects will not change unless an outside force is applied.
B) the objects can only collide if an outside force is applied.
C) any collisions between the objects must be elastic.
D) the total momentum of the objects cannot change unless an outside force acts on the system.

Accepted Answer

According to the law of conservation of momentum, the total momentum of a system cannot change unless an outside force acts on the system. Therefore, choice D is correct. Choices A and B are incorrect because the objects can exchange energy and collide without an outside force, as long as they interact through forces. Choice C is incorrect because collisions can be either elastic or inelastic, depending on the objects and the forces involved.

Quiz 7: Momentum and Impulse

The impulse required to bring an auto to a stop is ordinarily provided by __________________ forces.

A moving cue ball strikes another ball of equal mass that is initially at rest on the flat planar surface of the pool table. If the collision is elastic, the direction of the velocity of the cue ball after the collision will be __________________ to the direction of the velocity of the other ball.

A toy car and a toy truck at rest have a compressed spring in between them. The truck has more mass than the car. The spring is released and the two cars move in opposite directions. Which of the following is true?

A force acts on an object for a time. If one eighth the force had acted for twice as long, the impulse would have been __________ as much as before.

If a single force acts on a moving object

A rocket obeys the principles of recoil. However, it is much more difficult to apply Newton's second law to a rocket because

A 60 kg boy standing on a skateboard with frictionless wheels and negligible mass throws a 3 kg ball straight up with a speed of 4 m/s. If the boy was at rest before the throw, his speed after the throw will be _________________.

If the same impulse is applied to a ping-pong ball and a baseball, the change in the ping-pong ball's momentum will be _____________ the baseball's.

Two astronauts of equal mass are holding on to each other and moving at a speed of 30 m/s. They push off of each other and one of the astronauts moves in the same direction as the two were initially moving but at 60 m/s. The velocity of the second astronaut is

If a bullet is fired into a wooden block and remains lodged in the block, the collision was _________________.

The total momentum of a system will change during a collision unless the ____________ force is zero.

If heat, sound, or deformation of solid bodies results from a collision, there will be a change in the total __ .

If you were standing on a cart that was at rest and free to roll (ignore friction) and someone threw a 10 kg ball at you, you would

When a single boxcar in the freight yard hooks onto a stationary string of four boxcars, as in example 7.4, there is some kinetic energy lost. Which of the following could account for the missing energy?

If a bullet is fired into a solid wooden block and comes out the other side, the collision was _________________ inelastic.

Consider a system containing three objects that move with different velocities. The objects can interact with each other through forces. In this system