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The value of the friction force

  • Thread starter HazelDryad
  • Start date
  • #1

Homework Statement


The worker pushes downward and to the left on the box at an angle of 35°. The box has a mass of 135 kg. The box moves horizontally across the floor to the left at a constant velocity. The force applied by the man is 2030 N∠215°. What is the value of the friction force?


Homework Equations


Fgravity · sin35° = Fgravityx
Ffriction + Fgravityx = m · a
f = μ · Fs


The Attempt at a Solution


sin35° =
Fgravity · sin35° = Fgravityx
m · g · sin35° = Fgravityx
(135 kg)(9.81) sin35° = Fgravityx
759.6 N = Fgravityx

Ffriction + (759.6 N) = (135 kg)(0 m/s2)
Ffriction - 759.6 N = 0 N
Ffriction = 759.6 N

I know that this isn't correct, because my study guide is multiple choice. My options are:
a. 1164 N
b. 1324 N
c. 1663 N
d. 2489 N

I'm really not sure what I'm missing or if I am going the wrong way with finding the value of the friction force. My guess is that c. 1663 N is correct, but that is only a guess. I'd like to be able to prove which answer it is. Thank you for any help!
 

Answers and Replies

  • #2
rl.bhat
Homework Helper
4,433
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The worker pushes downward and to the left on the box at an angle of 35°
The force applied by the man is 2030 N∠215°

Can you explain what are these two angles? Whether the worker and the man are the same person?
 

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