Answer:
2100 J
Explanation:
Draw a picture. Notice that the rope forms a triangle, where the hypotenuse is L and the height is L cos θ. The height of the mass is h. The total height is L, so:
L = h + L cos θ
h = L − L cos θ
The work done by gravity is force times distance:
W = mgh
W = mg (L − L cos θ)
W = (75 kg) (9.8 m/s²) (12 m − 12 m cos 40°)
W = 2063 J
Rounding to two significant figures, the work done is 2100 J.
