Kinetic and Potential Energy: Build a Coaster
Understand that gravitational potential energy (m g h) converts into kinetic energy (½ m v²) as a cart descends, that the total stays fixed without friction, and that friction turns some of it into heat.
Before you try
What if you built a hill taller than the starting point? Would the cart ever get over it?
Try it out
Interactive activity
Sign in to play
Use a Google account (yours or a parent’s) to unlock this simulator. We store only your name and email so your favourites and progress follow you.
Signing in needs an internet connection. Once you are signed in, simulators also work offline.
Free preview
Loading controls…
What happened?
Move a control to see what changes and why.
The track is frictionless, so no energy is lost. A real coaster gives up energy to friction and air, which is why it never climbs as high again.
Something went wrong
This simulator could not load. Check your connection and try again.
Try these ideas
- Set hill 1 higher than the release height and watch the cart stop and roll back.
- Change only the cart mass. Does the top speed change?
- Turn on friction and find the extra release height needed to clear the same hill.
Why it works
Lift something up and you store energy in it: gravitational potential energy, equal to mass times gravity times height. Let it roll down and that store turns into kinetic energy, the energy of movement, equal to half the mass times speed squared. Energy is never made or destroyed, only converted, so on a perfectly smooth track the total stays the same and the cart can just reach any point at the same height it started from, never higher.
Here you set the release height, two hill heights, the dip and the mass, then release the cart and watch the potential and kinetic bars swap as it runs. Switch friction on and a small percentage of the energy is lost to heat for every metre of track, so the cart comes up short. That friction rule is a simple stand-in for the real forces between wheels, rail and air.
Check your understanding
Question 1 of 4
A cart is released from 10 m on a smooth track. What is the tallest hill it can get over?
Where on the track is the cart moving fastest?
Two carts, 200 kg and 800 kg, are released from the same height on a smooth track. Which is faster at the bottom?
With friction switched on, where does the missing energy go?
Explain it in your own words
What changed? Why did it happen? Where might you notice this in everyday life?
For parents & teachers
- Ask why a roller coaster always starts with its tallest climb.
- Roll a marble down a book ramp and time it from two different heights.
- Discuss where else energy changes form at home, such as in a torch or a kettle.