Answer:
19.95 J
Explanation:
The center of mass of the ladder is initially at a height of:
[tex]h_1=\frac{L}{2}sin\theta[/tex]
The center of mass of the ladder ends at a height of:
[tex]h_2= \frac{L}{2}sin90[/tex] =L/2
So, the work done is equal to the change in potential energy which is:
W = PE = [tex]mg(h_2-h_1)[/tex]
now [tex]h_2-h_1= 1-sin\theta[/tex]
therefore
W = [mgL/2]×[1 - sin(theta)]
W = [(7.30)(9.81)(2.50)/2]×[1-sin(51°)]
solving this we get
W = 19.95 J
