An interesting question concerning roller coaster.What's your view about the answers given in the worksheet?


The answer in the worksheet is

I agree with answers A & B, while differ in C.

A)
Roller coasters normally, do not have an engine; instead they rely on energy stored in the force of gravity, known as gravitational potential energy, to make it move. This is because there is effort carried out moving the cars from the ground to the top of the first hill.

The higher the peek, of the first hill, the greater the gravitational potential energy which is equal to the cars’ weight multiplied by the height of the hill.

B
As the cars begin down the hill, potential energy is transformed into kinetic energy until the cars reach the bottom of the hill. When the cars go up the next hill, some kinetic energy is transformed back into potential energy. This conversion continues throughout the ride until the cars come to a stop.

Some energy appears to be lost as the cars are not able to climb to the same height of the first hill and will eventually come to a complete stop. However, we know that energy cannot be created or destroyed but instead is converted to other forms of energy. In this particular case, the energy is changed to thermal energy (friction) which can be seen by an increase in temperature of the roller coaster’s track and car wheels.

C)
The picture, it not totally clear to me, however, from what I can see I do not necessarily agree with the diagram in the solution. The provided solution would require considerably more effort to move the cars through the first loop (since the initial hill has been eliminated) and the cars would come to an abrupt stop at the end. It does not appear to be an efficient design to me. Furthermore, the questions states that we are not to compromise the track design, which this solution has done. Note: Perhaps the initial hill has not been drawn in the solution.

My answer would be to increase the height of the initial hill thus having more gravitational potential energy at the start of the ride and / or decrease the height of the loop such that less energy is converted to friction.

Hi Chris

Here's a link about conversion of energy in a roller coaster.
www.hk-phy.org/oceanpark/rol/resource/rollercoaster_e8.swf

Have fun

Excellent.

This is very good visually, showing that the total amount of energy is constant (conservation of energy)and it is converted between PE and KE continuously.

Thanks Tianzhu