Lifting a piano into a truck is an example of doing negative work. A. True B. False
1 answer:
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Answer:
a) W = 5360 J b) μ = 0.29
Explanation:
a) The work is, bold indicate vectors
W = F. d = F d cos T
W = 40 268 cos 60
W = 5360 J
b) The force of friction and opposes the movement of the body and if the speed of the body is constant implies that the external force in the direction of the movement is equal to the force of friction, or which work is the same
= -5360J
The negative sign is because the force of friction is contrary to the direction of movement
c) Let's write the work of the friction force
= fr d cos 180
fr = μ N
Since the body is on a horizontal surface, from Newton's second law on the Y axis
N-W = 0
N = W
fr = μ W
= - μ W d
μ = - / W d
μ = - (-5360) / 69 268
μ = 0.29