Physics Semester 2 Final Concepts

An object hits a wall and bounces back with half of its original speed. What is the ratio of the final kinetic energy to the initial kinetic energy of the object?

1/4

A force produces power "P" by doing work "W" in a time "T". What power will be produced by a force that does six times as much work in half as much time?

12P

A 35-N bucket of water is lifted vertically 3.0 m and then returned to its original position. How much work did gravity do on the bucket during this process?

0 Joules of work

A tiger is running in a straight line. If we double both the mass and speed of the tiger, the magnitude of its momentum will increase by what factor? (how many times larger will the magnitude be?)

4

One calorie (c) of heat equals ____________.

4.186 J

Which requires more work, increasing a car's speed from 0 mph to 30 mph or from 50 mph to 60 mph?

50 mph to 60 mph

A 4.0 kg object is moving with speed 2.0 m/s. A 1.0 kg object is moving with speed 4.0 m/s. Both objects experience the same constant braking force and are brought to rest. Which object travels the greater distance before stopping?

Both objects travel the same distance.

Which degree measuring unit is the same size as Kelvin?

Celsius

A truck has four times the mass of a car and is moving with twice the speed of the car. If Kt and Kc refer to the kinetic energies of the truck and car respectively, it is correct to say that the equation is-

Kt=16Kc

Two men, Joel and Jerry, push against a car that has stalled, trying unsuccessfully to get it moving. Jerry stops after 10 minutes, while Joel is able to push for 5.0 minutes longer. Compare the work they do on the car.

Neither of them do any work on the car.

Consider two less-than-desirable options. In the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. In the second option you are driving 30 mph and crash head-on into a stationary brick wall. In neither cases does your car bounce back from the thing it hits, and the collision time is the same in both cases. Which of these two situations results in a greater impact force on your car?

The force would be the same in both cases

A small car meshes with a large truck during a head-on collision. What statement concerning the magnitude of the average force during the collision can be made?

The small car and the truck experience the same average force.

A small car meshes with a large truck in a head-on collision. What statement concerning the magnitude of momentum change of the collision can be made?

The small car and truck experience the same magnitude momentum change.

You throw a baseball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of work done by gravity while it goes down.

The work is negative on the way up and positive on the way down.

In a collision between two unequal masses, which mass receives the greater magnitude impulse?

They receive equal impulses

During World War I, Germany used a "Big Bertha" cannon to hurl shells into Paris 30 miles away. This gun also had a very long barrel. What was the reason for using a long barrel in these guns?

To allow the force of the expanding gases from the gunpowder to act for a longer time

Collisions are not possible if the momentum is not totally-

conserved

In a game of pool, the white cue ball hits the #5 ball and stops, while the #5 ball moves away with the same velocity as the cue ball had originally. Both balls have the same mass. This type of collision is-

elastic

Identical forces act for the same length of time on two different objects. The magnitude of the change in momentum of the lighter object is-

exactly equal to the magnitude of change in momentum of the larger mass

Jill does twice as much work as Jack does in half the time. Jill's power output is how much compared to Jack?

four times Jack's output

A stone is held at height "h" above the ground. A second stone with four times the mass of the first one is held at the same height. The gravitational potential energy of the second stone to the first stone is how many times more?

four times as much

The bigger the ____________ the slower an object heats up or cools down.

heat capacity

Adding thermal energy is known as ___________, and removing thermal energy is known as _______________.

heating ; cooling

The momentum of an isolated system is conserved-

in both elastic and inelastic collisions

Thermal expansion is proportional with __________________.

initial length AND temperature change

Thermal Equilibrium is achieved when two objects have the _____________________.

same temperature

A rubber ball and a lump of clay have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The clay sticks to the wall. Which of these objects experienced the greater momentum change?

the ball

What is temperature?

the measure of average kinetic energy of particles