Important Energy Concepts
These types of energy are included when we calculate total mechanical energy.
What are kinetic and potential (gravitational and/or spring).
Find the gravitational potential energy of a 0.15 kg baseball thrown to a maximum height of 12 m.
What is 17.6 J?
A rollercoaster with 100,000 J of gravitational potential energy at the top of a hill travels to the bottom of the hill along a frictionless track. Find the kinetic energy of the coaster at the bottom of the hill.
What is 100,000 J?
A 0.1 kg superball is dropped from rest at a height of 2 m. What is its speed just before it hits the ground?
What is 6.3 m/s?
These are the units used to measure work.
What are Joules (J)?
What is 141.8 J?
If you do 30 J of work to lift a bag of groceries onto a 0.8 m tall table, what is the gravitational potential energy of the bag once it's on the table?
What is 30 J?
A 0.1 kg superball is thrown upward at a speed of 12 m/s. Find the maximum height that it will reach. (Hint: assume it starts at a height of zero)
What is 7.3 m?
Define what it means for a system to be isolated.
No objects outside the system affect the energy of the system.
What is 0.54 J?
A ball sits at the top of a hill at rest, with a total mechanical energy of 100 J. Find its kinetic energy when it has rolled halfway down the hill.
What is 50 J?
A 100 kg roller coaster reaches the top of a 35 m hill with a speed of 20 m/s. When it reaches the bottom of the hill, how fast will it be moving?
[Answer pending]
When an object is thrown directly upward, what is its kinetic energy when it reaches its maximum height?
What is 0 J?
A 30 kg jogger runs up a hill to reach an elevation of 8 m, then turns around and runs back down the hill. The whole trip takes 70 seconds, and occurs at a constant speed of 2.5 m/s.
Find the kinetic energy of the jogger.
What is 93.8 J?
A 0.11 kg hamburger falls off of a 1 m tall table. When it is halfway to the floor, how much kinetic energy does it have?
What is 0.54 J?
[Answer pending]
Describe how doing work on a system will affect its energy.
A 1.5 kg textbook sits on a shelf, lonely, and waiting to be studied. It has 36.75 J of gravitational potential energy. Find the height of the shelf.
What is 2.5 m?
A 0.1 kg superball is thrown upward at a speed of 12 m/s. Find its gravitational potential energy when it reaches its maximum height (Hint: assume it starts at a height of zero.)
What is 7.2 J?
If an 5 kg barbell falls from a height of 2 m onto a spring-loaded platform with a spring constant of k=200 N/m, find the distance that it will compress the spring.
1 m