4. A person pulls a block on
horizontal surface by applying a
force of 5.0 N at an angle of
60° with the vertical. The work
done by this force in displacing
the block thorough 2.0 m will
be:
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PHYSICS
A block of mass m is pulled along a horizontal surface by applying a force at an angle θ with the horizontal. If the block travels with a uniform velocity and has a displacement d and the coefficient of friction is μ, then the work done by the applied force is:
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October 15, 2019
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Namit Prashant
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VIDEO EXPLANATION
ANSWER
Let the force applied on the block be F,
The surface applies a frictional force on the block in the backward direction.
Vertical direction :
N+Fsinθ=mg
N=mg−Fsinθ ........(1)
Horizontal direction:
As the block moves with a constant velocity,
so Fcosθ is balanced by f
∴ Fcosθ=f
Fcosθ=μN
Fcosθ=μ(mg−Fsinθ)
⟹F=
cosθ+μsinθ
μmg
Work done by the applied force
W
F
=
F
.
S
W
F
=Fdcosθ
⟹W
F
=
cosθ+μsinθ
μmgdcosθ
solution
Answer:
W=fcos60×s
W=5×1/2×2
W=5Nm
Explanation: