Question

A pendulum has 532 J of potential energy at the highest point of its swing. How much kinetic energy will it have at the bottom of its swing?

Answer 1

Answer:

532 J

Explanation:

If there are no frictional forces/air resistance involved in the problem, then the mechanical energy of the system is conserved.

This means that:

$E_i = E_f$

where E_i is the initial mechanical energy and E_f is the final mechanical energy. The mechanical energy is the sum of potential energy U and kinetic energy K:

$U_i + K_i = U_f + K_f$

At the highest point, the speed of the swing is zero, so

$K_i = 0$

while at the bottom point, the potential energy is zero (if we take the bottom point of the swing as reference level), so

$U_f =0$

This means that the previous equation becomes

$U_i = K_f$

and since

$U_i = 532 J$

the kinetic energy at the bottom of its swing is

$K_f = 532 J$