Question
The bob of a pendulum is released from a horizontal position. If the 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?
Solution
Let,
Mass of the bob = m
Length of the string = l
At B, P.E of the bob = 0
At A, P. E of the bob = mgl
When bob reaches the point B, 5% of the potential energy is dissipated against air resistance, and rest of 95% is converted in kinetic energy.
That is,
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, is the speed with which the boy arrives.
