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Question
A block of mass 50 kg moves on a rough horizontal surface with a coefficient of kinetic friction µ = 0.5. If the distance traveled is 20 m, how much work is done by the friction force? (take g = 10 m/s2)
A block of mass 50 kg moves on a rough horizontal surface with a coefficient of kinetic friction µ = 0.5. If the distance traveled is 20 m, how much work is done by the friction force? (take g = 10 m/s2)
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Solution
The correct option is D −5000 J
Frictional force, F=μN
where, N( normal force) =mg
μ =0.5 (given)
N=50×10=500 N
F=0.5×500=250 N
Work done by friction W=F.s
s=20 m (given)
W = 250×20=5000 J
But friction acts in opposite direction of displacement and we have to do work on the system to displace it, we took work done on the system as negative i.e −5000 J
Frictional force, F=μN
where, N( normal force) =mg
μ =0.5 (given)
N=50×10=500 N
F=0.5×500=250 N
Work done by friction W=F.s
s=20 m (given)
W = 250×20=5000 J
But friction acts in opposite direction of displacement and we have to do work on the system to displace it, we took work done on the system as negative i.e −5000 J