Question

A ball is suspended by a lightweight string, as shown in the figure above.

Answer 1

The answer is C: 3 and 4
proof:
the greatest value of the speed is on the number 4,
V1<V2<V3<V4; but we know that if the speed is higher, so is kinetic energy value. V4 is the speed having higher value (between 3 and 4)

Answer 2

Answer

A. 1 and 2

Explanation

At point 1 we have the highest potential energy and the kinetic energy is zero.

At 2 the potential energy is minimum and the kinetic energy is maximum.

The law of conservation of energy says that energy cannot be created nor destroyed. So, the change in P.E = Change in K.E.

P.E = height × gravity × mass. The height referred here is the perpendicular height. Gravity and mass are constant in this case.

From the diagram it can be seen clearly that the vertical height from 2 to 1 is much greater than from 4 to 3.

This shows that the change in P.E is greater between 1 and 2 and so is kinetic energy.