A person uses the above system to lift a load that weighs 1250N. a) Suppose our
ID: 1261164 • Letter: A
Question
A person uses the above system to lift a load that weighs 1250N.
a) Suppose our person lifts this load two meters slowly (at constant velocity). What force must he exert on the rope to do so?
b) Calculate the work done by the rope on the load, and calculate the work he does on the rope.
d) Explain why force does negative work by using the defenition of work (W=F*ds)
A person uses the above system to lift a load that weighs 1250N. a) Suppose our person lifts this load two meters slowly (at constant velocity). What force must he exert on the rope to do so? b) Calculate the work done by the rope on the load, and calculate the work he does on the rope. d) Explain why force does negative work by using the defenition of work (W=F*ds)Explanation / Answer
Here ,
as W = 1250 N
Now , for moving load at constant speed ,
Fnet = 0
2T - 1250 = 0
T = 625 N
the tension in the rope is 625 N
therefore , the force exterted on the rope is 625 N
b)
Work done by rope = 2*625 * 2
Work done = 2500 J
work done by the rope is 2500 J
Work done by person = work done by rope
Work done by person = 2500 J
d)
here , gravity does negative work , as the force is oposite to the displacement
hence , Work done = F*d*cos(180) = -ve
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