Question

5. The bob of a simple pendulum is imparted a velocity
of 5 m - when it is at its mean position. To what
maximum vertical height will it rise on reaching at
its extreme position if 60% of its energy is lost in
overcoming the friction of air ?
(Take g = 10 m s-2).
Ans. 0.5 m​

Answer 1

Answer:

When it is at mean position it will have a K.E  of  0.5mv  

2

.

K.E=0.5×m×5×5=12.5×m J

60 % of this K.E is lost hence remaining  is equal to (40/100)12.5×m=5m

P.E=mgh=5×m

h=5/g=5/10=0.5m

Hence it goes to  a height of 0.5m.