Plugging in values

Using

Using

Using

Initially the space ship is motionless, so it has  kinetic energy

There will be no work done.

Energy is a scalar quantity. Since it has the same amount of energy in the end as the beginning, no work was done.

Alternatively, it can be modeled as the floor did negative work during the first half of the bounce (when the ball was compressing), and did positive work of the same magnitude and opposite sign in the second half of the bounce. This is due to the direction of the ball's motion flipping and the Force vector of the floor staying the same.

Based on the information given, his throw would have started at  above the ground. The pizza gained a maximum height of . Thus, the gravitational potential energy in relation to the starting position will be:

Since at it's maximum height, all of the energy will be gravitational, the work done on the pizza will be equal to the potential energy, thus:

Using

Initially the car is at rest at the bottom of a hill, this velocity and height are zero.

Converting  to 

Plugging in values:

The equation for work is:

Where  is the work done on an object,  is the force applied to an object,  is the distance the object moves, and  is the angle between the applied force and the direction the object moves.

From the problem statement we have:

 but .

Plugging in to our equation we find:

Because the rock does not move, no work is done on the rock. 

Note: the unit for work is shown to be  and a Newton-meter is the same as a Joule so  would also be an appropriate answer.

The equation for work is:

Where  is the work done on an object,  is the force applied to an object,  is the distance the object moves, and  is the angle between the applied force and the direction the object moves.

From the problem statement we have:

 and .

Plugging in to our equation we find:

We can assume that the bulldozer is pushing straight in to the rock because no information is given about the angle between the force and distance, so we can assume that  and  and that part of the formula can be ignored in this problem.

The time it takes to move the rock is superfluous information as work does not have a time component.

Note: the unit for work is shown to be  and a Newton-meter is the same as a Joule so  would also be an appropriate answer.

This question asks you how to calculate the work done by gravity on a block that is dropped from the air. Work is calculated by multiplying a given force by the distance over which the force acts. In this case, you are asked to find the work done strictly by the force of gravity on the block. The force of gravity works over the distance from which the block is dropped, to the ground (i.e. the height of the block, ). Thus, you can set up the equation as follows:

Therefore, the work done by gravity on the block is 

Work is found by finding the change in kinetic energy. Since the car started from rest it had no initial kinetic energy.

Divide by 1000 to convert to kilojoules and get 5400 kilojoules.