Mastering Physics 8

4.7 x 10^4 N

A 1700kg rhino charges at a speed of 50.0km/h. What is the magnitude of the average force needed to bring the rhino to a stop in 0.50s?

24 N

A 3.6-kg chihuahua charges at a speed of 3.3m/s. What is the magnitude of the average force needed to bring the chihuahua to a stop in 0.50s?

Car B

After 10 s which car has a larger kinetic energy? Car A Car B Both cars have the same kinetic energy.

Both cars have the same momentum

After 10 s which car has a larger momentum? Car A Car B Both cars have the same momentum.

P⃗ A,i+P⃗ B,i=P⃗ A,f+P⃗ B,f ΔP⃗ A+ΔP⃗ B=0

Bumper cars A and B undergo a collision during which the momentum of the combined system is conserved. Which equation(s) correctly states the principle of conservation of momentum? Check all that apply. P⃗ A,i+P⃗ B,i=P⃗ A,f+P⃗ B,f P⃗ A,i+P⃗ A,f=P⃗ B,i+P⃗ B,f ΔP⃗ A=ΔP⃗ B ΔP⃗ A+ΔP⃗ B=0

equal to

During the explosion, is the magnitude of the force of piece A on piece B greater than, less than, or equal to the magnitude of the force of piece B on piece A?

1/2K

If the kinetic energy of the lighter cart after the push is K, the kinetic energy of the heavier cart is 1/4K 1/2K K 2K 4K

P

If the magnitude of the momentum of the lighter cart after the push is P, the magnitude of the momentum of the heavier cart is 14P 12P P 2P 4P

An object's momentum is equal to the product of its mass and its velocity. Momentum is a vector quantity.

In the opening scenes of the prelecture video, we outlined some of the key properties of momentum. Which of the following statements are consistent with these properties? Check all that apply. An object's momentum is equal to its mass divided by its velocity. An object's momentum is equal to the product of its mass and its velocity. Momentum is a vector quantity. Momentum is a scalar quantity.

B > C=A

Object A has a mass m and a speed v, object B has a mass m/2 and a speed 4v, and object C has a mass 3m and a speed v/3. Rank the objects according to the magnitude of their momentum.

pAx,f = -500 kg⋅m/s

The component of the momentum of piece B, pBx,f, is measured to be +500 kg⋅m/s after the explosion. Find the component of the momentum pAx,f of piece A after the explosion.

The "glue force" cancels the collision force.

The video shows an animated billiards experiment in which a cue ball strikes a glued-in-place eight-ball. Which of the following explains why the momentum of the eight-ball is conserved? The eight-ball is an isolated system. The cue ball rebounds with the same speed it had coming in. The "glue force" cancels the collision force. The collision is elastic.

They all have the same amount of momentum.

Three cars, car X, car Y, and car Z, begin accelerating from rest at the same time. Car X is more massive than car Y, which is more massive than car Z. The net accelerating force exerted on each car is identical. After 10 seconds, which car has the most amount of momentum? They all have the same amount of momentum. Car X Car Y Car Z

p1+p2≥p≥|p1−p2|

Two cars collide inelastically and stick together after the collision. Before the collision, the magnitudes of their momenta are p1 and p2. After the collision, the magnitude of their combined momentum is p. Of what can one be certain? p1+p2≥p≥√p1p2 p1+p2≥p≥(p1+p2)/2 p1+p2≥p≥|p1−p2| p1+p2≥p≥√p1^2+p2^2

The answer depends on the directions in which the cars were moving before the collision.

Two cars collide inelastically and stick together after the collision. Before the collision, the magnitudes of their momenta are p1 and p2. After the collision, what is the magnitude of their combined momentum? p1+p2 p1−p2 p2−p1 √p1p2 (p1+p2)/2 √p1^2 +p2^2 The answer depends on the directions in which the cars were moving before the collision.

p⃗ =p1→+p2→

Two cars collide inelastically and stick together after the collision. Before the collision, their momenta are p⃗ 1 and p⃗ 2. After the collision, their combined momentum is p⃗ . Of what can one be certain? p⃗ =p1→+p2→ p⃗ =p1→−p2→ p⃗ =p2→−p1→

The answer depends on the directions in which the cars were moving before the collision.

Two cars of equal mass collide inelastically and stick together after the collision. Before the collision, their speeds are v1 and v2. What is the speed of the two-car system after the collision? v1+v2 v1−v2 v2−v1 √ (v1v2) (v1+v2)/2 √ ( v1^2+v2^2) The answer depends on the directions in which the cars were moving before the collision.

0

What is the magnitude of the momentum |p⃗ A,i| of piece A before the explosion?

the net momentum (considered as a vector) only

What physical quantities are conserved in this collision? the magnitude of the momentum only the net momentum (considered as a vector) only the momentum of each object considered individually

Car B wins

Which car crosses the finish line 1.0 m away first? Car A wins Car B wins Both cars cross the finish line at the same time.

Car A

Which car has a larger momentum when it crosses the finish line 1.0 m away? Car A Car B Both cars have the same momentum.

Both cars have the same kinetic energy.

Which car has the larger kinetic energy when it crosses the finish line 1.0 m away? Car A Car B Both cars have the same kinetic energy.

Car B

Which car has traveled farther after 10 s? Car A Car B Both cars travel the same distance.

A

Which of the following arrows indicates the direction of the impulse applied to ball A by ball B?

C

Which set of arrows best represents the change in momentum for balls A and B?

The net external force on the system is zero.

Which statement must be true for the momentum of a system to be conserved? The internal forces sum to zero. The net external force on the system is non-zero. The net external force on the system is zero. There are no external forces acting on the system.

The right shoe

While goofing off at the ice skating rink, a student takes off her shoes and places each of them on the ice. Her friend, a hockey player, then shoots a hockey puck at each shoe. The first puck immediately comes to rest after it collides with the left shoe. The second puck rebounds after it collides with the right shoe. If each hockey puck has the same incoming speed, which shoe has greater speed after the collision? Both shoes have the same speed. The left shoe The right shoe