Q.

The bob of a pendulum was released from a horizontal position. The length of the pendulum is 10 m. If it dissipates 10% of its initial energy against air resistance, the speed with which the bob arrives at the lowest point is ______.

[Use, g = 10 ms-2]                          [2024]

1 65 ms-1  
2 55 ms-1  
3 25 ms-1  
4 56 ms-1  

Ans.

(1)

=10 m,

Initial energy =mg

So, 910mg=12mv2

  910×10×10=12v2

v2=180

v=180=65 m/s