A factory worker pushes a 29.1 kg crate a distance of 5.0 m along a level floor
ID: 1339329 • Letter: A
Question
A factory worker pushes a 29.1 kg crate a distance of 5.0 m along a level floor at constant velocity by pushing downward at an angle of 32 below the horizontal. The coefficient of kinetic friction between the crate and floor is 0.24.
Part A
What magnitude of force must the worker apply to move the crate at constant velocity?
Express your answer using two significant figures.
F=
N
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Part B
How much work is done on the crate by this force when the crate is pushed a distance of 5.0 m ?
Express your answer using two significant figures.
W=
J
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Part C
How much work is done on the crate by friction during this displacement?
Express your answer using two significant figures.
Wf=
J
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Part D
How much work is done by the normal force?
Wnf=
J
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Part E
How much work is done by gravity?
Wg=
J
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Part F
What is the total work done on the crate?
Wnet=
Explanation / Answer
A) Let F is minimum applied force is needed.
When, Fnetx = 0, the crate moves with constant speed.
F*cos(32) - mue_k*N = 0
F*cos(32) - mue_k*(m*g + F*sin(32)) = 0
F*(cos(32 - mue_k*sin(32)) = mue_k*m*g
F = mue_k*m*g/(cos(32) - mu_k*sin(32))
= 0.24*29.1*9.8/(cos(32) - 0.24*sin(32))
= 95 N
B) W(applied force) = F*d*cos(32)
= 95*5*cos(32)
= 402.8 J
C) Workdone by friction = -402.8 J
D) Workdone by normal force = 0
E) Workdone by gravity = 0
F) Total Workdone = 0
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