The bob of a simple pendulum is imparted a velocity 5m/s when it is at its mean position. To what maximum vertical height will it rise on reaching its extreme position if 60% of its energy is lost in overcoming friction of air?

(Take g=10m/s^2)

Question

The bob of a simple pendulum is imparted a velocity 5m/s when it is at its mean position. To what maximum vertical height will it rise on reaching its extreme position if 60% of its energy is lost in overcoming friction of air?

(Take g=10m/s^2)

amistre64 · Answer

potential energy is equal to 60% of the kinetic energy ...

mgh = .6/2 mv^2 

gh = .6/2 v^2 

h = .6/(2g)  v^2

anonymous · Answer

is it not mgh =0.4/2 mv^2 since 60% is lost ?