To pull a 50 kg crate across a horizontal frictionless floor, a worker applies a force of 210 N, directed 20° above the horizontal. As the crate moves 3.0 m, what work is done on the crate by (a) the worker's force, (b) the gravitational force on the crate, and (c) the normal force on the crate from the floor? (d) What is the total work done on the crate?

Question

Gustavo

Physics

20 May, 02:32

To pull a 50 kg crate across a horizontal frictionless floor, a worker applies a force of 210 N, directed 20° above the horizontal. As the crate moves 3.0 m, what work is done on the crate by (a) the worker's force, (b) the gravitational force on the crate, and (c) the normal force on the crate from the floor? (d) What is the total work done on the crate?

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Answers (1)

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Munchkin · Answer 1

Given that,

A crate of mass M = 50kg

The crate is pulled along an horizontal floor by a string at an angle

Force pulling the crate

F = 210N

Angle θ = 20° to the horizontal

Distance moved by crate d=3m

A. Work done by force

W = FdCosθ

W = 210 * 3 * Cos20

W = 592J

B. Work done by Gravitational force?

Work is define as the dot product of force and displacement in the direction of the force.

Since the gravitational force does not cause the crate to move any distance downward

Then,

W (gravity) = mg*d

distance d=0

W (gravity) = 0 J

C. Work done by normal?

Since, the normal force did not cause the crate to move upward by any distance

Then,

W (normal) = 0J

D. The total workdone?

The only workdone on the crate is by the person

Then, the total workdone is the workdone by the person

W = 592 J