AS-LEVEL: Conservation of Energy QP (PMT AQApre2016)

Question 1

In the 17th century, when thinking about forces, Galileo imagined a ball moving in the absence of air resistance on a frictionless track as shown in Figure 1.

Galileo thought that, under these circumstances, the ball would reach position C if released from rest at position A. Position C is the same height above the ground as A.
Using ideas about energy, explain why Galileo was correct.

(3 marks)

Answer 1

-air resistance & friction are negligible, ∴ no work done against resistive forces

-GPE to Ek to GPE

• ∴ initial GPE = final GPE (ball reaches the same height)