Question

1. when a roller coaster is at the top of a hill, it has:

a) maximum kinetic energy
b) minimum potential energy
c) maximum potential energy
d) no energy

Explanation:

The formula for gravitational potential energy is \(U = mgh\), where \(m\) is mass, \(g\) is the acceleration due to gravity, and \(h\) is height. At the top of the hill, the height \(h\) is maximum. Since \(m\) and \(g\) are constant for the roller - coaster (assuming no mass change and constant \(g\) near the Earth's surface), when \(h\) is maximum, the potential energy \(U\) is maximum. Kinetic energy \(K=\frac{1}{2}mv^{2}\). At the top of the hill, the roller - coaster is usually moving slowly (velocity \(v\) is small), so kinetic energy is not maximum. And the roller - coaster always has energy (either potential or kinetic or both), so options A, B, and D are incorrect.

Answer:

C. Maximum potential energy