Coaster Creator Build an initial hill to put energy into your coaster, then add hills and loops. Too little energy and it gets stuck. Too much and it crashes into the end station. Can you get it to stop safely?

1. Cart Design. Give your coaster a name. Pick a pattern, a main color and a detail color. Press Next.
2. Cart Length. Use the slider to choose how many cars are in the train. Watch the mass change in the PE and KE equations at the top.
3. Track Design. The first hill is the chain lift. It puts energy into your coaster. Click any black node to see its buttons: build hill, build loop, or delete. For a hill, move your mouse to a white line on the right and click. For a loop, move your mouse up or down to size it and click. Nodes sit on the white lines; drag one up or down to change its height. Keep building until your track reaches COASTER END.
4. Coaster Test. Press Play. The chain pulls the train up the first hill, then lets it go. The train must reach the end station slowly enough for the brakes to stop it. Watch the bar: red PE is potential energy, green KE is kinetic energy, and orange TE is thermal energy made by friction and air.
5. Read the numbers. The equations at the top fill in with the train's mass, height and speed as it moves. Press Whole track to see the full ride at once.
6. Debrief. After the ride, a graph shows how the energy changed over time. Red is PE, green is KE and orange is thermal energy. Drag the green circle along the bottom to read the energy, speed and height at any moment.
7. Final Score. You earn points for hills, loops, screams, top speed and how well you used the brakes. Hover over each line to learn how to raise it.
8. Fix and try again. Stuck? It needs more energy, or lower hills. Crashed? It has too much energy at the end. Raise the end of the track or use up energy with more track. Press Back, change the track, and test it again.
9. Keyboard: in Track Design, click the picture, then use Tab to pick a node, arrow keys to move it (hold Shift for bigger steps), H to add a hill after it, L for a loop and Delete to remove it. In Coaster Test, Space plays and pauses.

Potential energy (PE) is energy stored by height. A heavier train, or a higher train, stores more: PE = m · g · h. Here g is 9.81 m/s², the pull of gravity.

Kinetic energy (KE) is energy of motion: KE = ½ · m · v². Speed is squared, so going twice as fast means four times the kinetic energy.

The chain lift does work on the train. It pulls it up the first hill and gives it all of its energy. After that, nothing adds energy. As the train drops, PE turns into KE. As it climbs, KE turns back into PE.

Thermal energy (TE) is heat. Friction in the wheels and air rubbing on the train slowly turn some energy into heat. That energy is not destroyed, but it can't move the train anymore. So no hill after the lift can be as tall as the lift hill.

At the end station, brakes turn the train's last kinetic energy into thermal energy. Brakes can only take so much. If the train still has too much kinetic energy when it gets there, it crashes. A higher end station leaves more of the energy as PE, so there is less KE for the brakes.

A loop needs speed. At the top, the train is upside down. It must be moving fast enough to stay pressed against the track. Big loops need more speed than small ones.

Force on riders is measured in g. At 1 g you feel your normal weight. At the bottom of a drop or loop you feel heavier. Over a hilltop you can feel weightless (airtime). Real coasters stay under about 5 g. This sim won't crash because of g-forces, but the results will tell you if riders felt too much.

The track is a smooth curve through your nodes. Loops are teardrop-shaped, like real ones. Their curve starts gently and gets tightest at the top, so riders aren't slammed at the bottom. The chain lift moves the train at a steady 5 m/s, so the energy at the top of the lift is mgh + ½mv². The energy bar is scaled to that amount, so you can watch the lift fill it up. After the lift, rolling friction (μ × the force between the wheels and track) and air drag turn energy into heat. The brakes at the end slow the train at 4 m/s² over 26 m, so they can stop a train arriving at up to about 14 m/s (50 km/h). Friction grows with mass but air drag does not, so a heavier train coasts a little farther. The train is tracked by its front car.