Question

a rock falls off a high cliff to the ground below. ignoring friction, which statement correctly compares the energy of the rock at different points of its fall? *hint: this is similar to the penny problem, we did in class.

○ a) the total energy just before it falls is less than its total energy half - way down.

○ b) the total energy just before it hits the ground is less than its total energy just before it falls.

○ c) the total energy just before it hits the ground is greater than its total energy half - way down.

○ d) the total energy just before it falls is equal to its total energy just before it hits the ground.

Explanation:

According to the law of conservation of energy, in the absence of non - conservative forces (like friction, which is ignored here), the total mechanical energy (sum of kinetic and potential energy) of the rock remains constant throughout its fall.

Answer:

D. The total energy just before it falls is equal to its total energy just before it hits the ground.