Physics Chapter 6 Test

In a/an _____ collision, the colliding objects rebound from each other. _____ Describe with a phrase another observable property of this type of collision.

Elastic, No heat generated

Forces exerted on system members by objects outside the system are called _____ forces. Hint: the answer is NOT "outside," even though the idea of "outside" is useful for figuring out this one word answer.

External

In the absence of a net _____ force, the total momentum of a system of objects will remain constant.

External

A bullet is fired from a gun rigged on a frictionless wire. The speed of the bullet will be about the same as the speed of the recoiling gun (A) because momentum is conserved. (B) if the mass of the bullet is much greater than the mass of the gun. (C) if the mass of the gun is much greater than the mass of the bullet.(D) if the mass of the bullet equals the mass of the gun. (E) because of none of these reasons.

(D) if the mass of the bullet equals the mass of the gun.

Padded dashboards in cars are safer in an accident than nonpadded ones because an occupant hitting the dash has (A) an increased time of impact. (B) a decreased impulse. (C) a decreased impact force. (D) both A and B. (E) both A and C.

(E) both A and C.

A 1 N apple falls to the ground. The apple hits the ground with an impact force of about (A) 1 N. (B) 2 N. (C) 4 N. (D) 9.8 N. (E) who knows....not enough information given to say.

(E) who knows....not enough information given to say.

A sandbag is motionless in outer space. A second sandbag with 3 times the mass moving at 12 m/s collides with it and they both stick together, and move at a speed of (A) 3 m/s. (B) 4 m/s. (C) 6 m/s. (D) 8 m/s. (E)none of these.

(E)none of these.

The __(2)__ exerted on an object is equal to the __(3)__ acting on the object multiplied by the __(4)__ that the __(5)__ acts.

Impulse, Force, Time, Force

In a/an _____ collision, the colliding objects stick together. _____ Describe with a phrase another observable property of this type of collision.

Inelastic, Heat is generated

Forces exerted on system members by other system members are called _____ forces. Hint: the answer is NOT "inside," even though the idea of "inside" is useful for figuring out this one word answer.

Internal

The _____ of an object is equal to its mass multiplied by its velocity.

Momentum

The impulse acting on an object is equal to the change in the _______ of the object.

Momentum

Air bags in automobiles help to save your life by increasing the _____ and therefore decreasing the ______.

Time, Force

Any quantity in physics that requires both a magnitude and a direction to be fully described is called a/an _______.

Vector

A ball is moving at 4 m/s and has a momentum of 48 kg•m/s. What's the ball's mass? (A) 4 kg. (B) 12 kg. (C) 48 kg. (D) 192 kg. (E) none of these.

(B) 12 kg.

The difference between impulse and impact force involves the (A) distance over which the force acts. (B) time during which the force acts.(C) difference between acceleration and velocity. (D) mass and its effect on resisting a change in momentum.

(B) time during which the force acts.

A 1000-kg car moving at 10 m/s brakes to a stop in 5 seconds. The magnitude of the average braking force is (A) 1000 N. (B) 2000 N. (C) 3000 N. (D) 4000 N. (E) 5000 N.

(B) 2000 N.

The impulse-momentum relationship is a direct result of (A) Newton's lst Law (Law of Inertia). (B) Newton's 2nd Law (Law of Acceleration). (C) Newton's 3rd Law (Law of Interaction).

(B) Newton's 2nd Law (Law of Acceleration).

Conservation of momentum is most closely related to (A) Newton's 1st Law. (B) Newton's 2nd Law. (C) Newton's 3rd Law.

(B) Newton's 2nd Law.

Suppose an astronaut in outer space wishes to play a solitary "throw, bounce, and catch" game by tossing a ball against a very massive and perfectly elastic wall. If the ball is as massive as the astronaut, the (A) astronaut will catch one bounce only. (B) astronaut will never catch the first bounce. (C) astronaut's time between catches will decrease as the game progresses. (D) astronaut's time between catches will increase as the game progresses.

(B) astronaut will never catch the first bounce.

It is correct to say that impulse is equal to (A) momentum. (B) the change in momentum. (C) the force multiplied by the distance the force acts. (D) all of these. (E) none of these

(B) the change in momentum.

Two billiard balls having the same mass and the same speed roll directly toward each other. Before the collision, what is the combined momentum of the two balls? (A) 0 kg•m/s. (B) 10 kg•m/s. (C)who knows....more information is needed to determine this.

(A) 0 kg•m/s.

A 4 kg ball has a momentum of 12 kg•m/s. What's the ball's speed? (A) 3 m/s. (B) 4 m/s. (C) 12 m/s. (D) 48 m/s. (E) none of these.

(A) 3 m/s.

When you are in the path of a fast-moving object and can't get out of its way, you will suffer a smaller force of impact if you decrease its momentum over (A) a long time. (B) a short time. (C) either a short or a long period of time.

(A) a long time.

When you jump from a table to the floor, you usually bend your knees upon reaching the ground. By doing this, the time of the impact is about 10 times more than for a stiff-legged landing. In this way the average force your body experiences is reduced by (A) about 10 times. (B) more than 10 times. (C) less than 10 times.

(A) about 10 times.

You're driving down the highway and a bug spatters into your windshield. During the time of the collision, which undergoes the greater change in velocity? (A) the bug. (B) your car. (C) neither...both are the same.

(A) the bug.

A fan attached to an ice sail craft stalled on a windless day blows air into the sail that bounces backward upon impact. This boat can (A) then move in the direction of the wind impact force. (B) not move by this wind impact force. (C) then move, but in the opposite direction of the wind impact force.

(A) then move in the direction of the wind impact force.

Recoil is noticeable if we throw a ball while standing on roller stakes. If instead we go through the motions of throwing the ball but hold onto the ball, our net recoil will be (A) zero. (B) the same as when you throw the ball. (C) small, but noticeable

(A) zero

A 1-kg chunk of sticky clay is moving across a frictionless surface at 1 m/s, collides and sticks to a 5 kg bowling ball initially at rest. The bowling ball and clay then move together with a momentum of (A) 0 kg•m/s. (B) 1 kg•m/s. (C) 2 kg•m/s. (D) 5 kg•m/s. (E) more than 5 kg•m/s.

(B) 1 kg•m/s.

A golf ball moving in a straight line to the right with 1 unit of momentum strikes and bounces directly backwards (i.e., in a straight line to the left) off a heavy bowling ball. The heavy bowling ball is initially at rest and free to move on a frictionless surface. Assuming a perfectly elastic collision between the golf ball and the bowling ball, the bowling ball is set in motion in a straight line to the right with a momentum of (A) less than 1 unit. (B) more than 1 unit. (C) 1 unit. (D) who knows....not enough information to tell.

(C) 1 unit.

Consider massive carts that slide friction free along a horizontal track. Cart A has a mass of 1 kg, a speed of 1 m/s to the right, and collides with Cart B that has a mass of 5 kg and is at rest. If they stick upon collision, their speed after collision will be (A) 1/4 m/s. (B) 1/5 m/s. (C) 1/6 m/s. (D) 1 m/s. (E) none of these.

(C) 1/6 m/s.

Which of the following has the largest momentum? (A) a tightrope walker with a mass of 50 kg walking across Niagara Falls at 0.5 m/s. (B) a pickup truck with a mass of 2000 kg speeding along a highway at 35 m/s. (C) a supertanker with a mass of 400,000 kg coasting toward the dock at 1 m/s. (D) the Kirby Physics Building with a mass of 1 million kg at rest relative to you. (E) a barking dog with a mass of 10 kg running down a street at 8/ms.

(C) a supertanker with a mass of 400,000 kg coasting toward the dock at 1 m/s.

Compared to the force that brings a light car to a stop, the force required to bring a heavy truck traveling at the same speed to a stop (A) is less. (B) is more. (C) may be less or may be more.

(C) may be less or may be more.

A moving object on which no forces are acting will continue to move with constant (A) acceleration. (B) impulse. (C) momentum. (D) all of these. (E) none of these.

(C) momentum.

A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has four times as much mass, its momentum is (A) zero. (B) doubled. (C) quadrupled. (D) unchanged.

(C) quadrupled.

A rifle of mass 2 kg is suspended horizontally by a frictionless metal wire and is at rest. By means of electronic remote control, the rifle fires a bullet with a mass of 1/100 kg at a speed of 200 m/s. The magnitude of the recoil velocity of the rifle is (A) 0.001 m/s. (B) 0.01 m/s. (C) 0.1 m/s. (D) 1 m/s. (E) none of these velocities.

(D) 1 m/s.

According the Law of Conservation of Momentum, the total momentum of a system before an event involving internal forces is _____ (<, =, >) the total momentum of a system after the event.

=

When the total amount of a quantity remains the same before and after an event, we say the quantity is _______. (your answer must be a technical physics vocabulary word).

Conserved