Answer to Question #234406 in Mechanics | Relativity for ibrahin

Question

[04:20, 07/09/2021] Ibrahim Mohamed: Batman, whose mass is 80.0kg, is dangling on the

free end of a 12.0-m rope, the other end of which is fixed

to a tree limb above. He is able to get the rope in motion

[04:21, 07/09/2021] Ibrahim Mohamed: as only Batman knows how, eventually getting it to swing

enough that he can reach a ledge when the rope makes a

60.0°angle with the vertical. How much work was done by

the gravitational force on Batman in this maneuver?

Answer 1

$g = 9.8\frac{m}{s^2}$

$l = 12m$

$m = 80kg$

$\alpha=60\degree$

$W_g= mg\Delta h$

$\Delta h = l*\cos \alpha-l= 12*\cos60\degree-12=-6m$

$W_g= 80*9.8*(-6)= -4707J$

$\text{Answer: The work of gravitational force equal }-4707\ J.$