. The bob of a simple pendulum is imparted a velocity of 5m s-1 when it is at its mean position


The bob of a simple pendulum is imparted a velocity of 5m s-1 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).

 

Best Answer

Total kinetic energy at mean position = 1 / 2 mv2

= 1 / 2 m × 52

Energy lost = 1 / 2 m × 52 × 60 / 100

Energy available = 1 / 2 m × 52 × 40 / 100

According to energy conservation

1 / 2 m × 52 × 40 / 100 = mgh

5 = 10 × h

h = 0.5m

 

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