Question

The bob of a pendulum is released from a horizontal position. Length of the pendulum is 1.5 m. what is the speed with which the bob arrives at the lowermost point. given that it dissipated 5% of its initial energy against air resistance?

• A. 5.28 m/s
• B. 8 m/s
• C. 18 m/s
• D. 25 m/s

Answer 1

The correct option is A 5.28 m/s

Initial Energy of Pendulum = Final energy +loss

$\Rightarrow mgL=\frac{1}{2}m{v}^2+0.05\left(mgL\right)$

$\Rightarrow 0.95mg\left(1.5\right)=\frac{1}{2}m{v}^2$

$\Rightarrow v^2=27.93$

$\Rightarrow v=\sqrt{27.93}=5.28m/s$

Therefore, A is correct option.