AP Physics 1 : Work, Energy, and Power
Study concepts, example questions & explanations for AP Physics 1
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Example Questions
Example Question #11 : Work, Energy, And Power
A model rocket weighing 5kg has a net propulsion force of 50N. Over a small period of time, the rocket speeds up (with constant acceleration) from an initial velocity of 
The net work done is equal to the change in kinetic energy. So we must find the kinetic energy at both the initial and final velocities and subtract.
Example Question #11 : Work
A large block is sitting on the floor. The block is 
First let's draw a free body diagram of the block with all the forces acting on it.
The block has a weight force which is 
The work done is just the product of the applied force and the distance the block slides,
Work is an energy, and the units of 
Example Question #11 : Work, Energy, And Power
Consider a constant force, given below, that acts on an object as it moves along the path 
In order to find the work done on the object, we need to take the dot product of the force and the path taken. This is a direct calculation.
Example Question #11 : Work, Energy, And Power
A rocket is in space at location 
What is the work done on the rocket by the thrusters?
None of these
Because all of the force was in the Y direction, all of the work will come from the change in the Y coordinate.
We will use the definition of work
First we need to find the distance traveled.
Then we can plug that into our work equation.
Example Question #14 : Work
You are pulling a dolly with special frictionless wheels on a level surface. There is a rope from your hand to the dolly which you are using to pull it with. The rope makes a 
How much work is done on the dolly over a distance of 
None of these
The definition of work is
Where
and 
The angle will be 
We plug in our values
Example Question #15 : Work
A car of mass 
Determine the work done on the car in this time frame.
None of these
Use the definition of work:
Plug in known values and solve.
Example Question #11 : Work, Energy, And Power
A pitcher throws a baseball of mass 
All of the 
Convert 
Solve for
Example Question #17 : Work
A train of mass 
Use work:
All energy will be kinetic.
Convert 
Plug in values. Force will be negative as it is directed against the direction of travel:
Solve for 
Example Question #18 : Work
Which of the following variables are involved in the calculation of work?
I. Force
II. Distance
III. Acceleration
I only
I and II
I, II and III
II only
I, II and III
Work is defined as:
Where 
Where 
Example Question #19 : Work
A person pushes a heavy stone down a hill. The stone weighs 
Cannot be determined from the given information
Cannot be determined from the given information
To solve this question, we need to recall the definition of work.
To calculate work, we need to know about the distance travelled, mass, and acceleration. The question gives us the distance and mass but it doesn’t give us the acceleration of the object; therefore, we cannot calculate the work done by the person. Note that if the question gave us the force applied by the person, then we will be able to calculate the work without mass and acceleration.
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