Problem 7-51 Energy cons. - Part 2 - A

A boy is playing with a rope tied to a tree near his favourite swimming hole. Initially the boy is stationary and the rope (of length $3.7 \;m$) makes an angle of $48^\circ$ with the vertical. He then lifts his feet slightly and starts to swing freely. If air resistance is neglected, use conservation of energy to determine:

(a) his speed at the bottom of the swing
(b) the minimum height, relative to his initial position, to which he can swing.

Accumulated Solution

At point 2, $E_P = 0$

Correct.

At point 2, $E_P = 0$

What is the kinetic energy $E_K$ at point 2?

(A)   $0$

(B)   $mgh$

(C)   $(1/2)mv^2$