The two ropes seen in (Figure 1) are used to lower a 255 kg piano exactly 4 m from a second-story window to the ground.
https://session.masteringphysics.com/problemAsset/1810667/5/102.jpg
A)How much work is done by w⃗ ?
B)How much work is done by T⃗ 1?
C)How much work is done by T⃗ 2?
?
If you find the vertical components of the tensions in the ropes (1830 sin 60 and 1295 sin 45), you will see they equal the weight of the piano, so that the piano is being lowered at a constant speed (with no accleration)
the work done by a force is force in the direction of motion x displacement
so the work done by the ropes is - T sin(theta) x 4m
T sin(theta) is the vertical component of force, 4m is the distance, and the minus sign indicates that the force (due to the ropes) is opposite the direction of motion
the work done by gravity is simply 2500N x 4m and is positive since the force is in the direction of motion
A) Work done by w⃗ = 2500N x 4m
B) Work done by T⃗1 = - 1830 sin 60 x 4m
C) Work done by T⃗2 = - 1295 sin 45 x 4m
JJ
I think the answer is:
B)How much work is done by T⃗ 1?