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Wedge Problem

  • Thread starter Lancelot59
  • Start date
  • #1
634
1
I've tried a whole manner of different things to try and solve this:

Prob.8-67.jpg


Determine the smallest force P needed to lift this 150kg cylinder.
Coefficients of static friction
At A: 0.7
At B: 0.3
At C: 0.4

I've tried different things and I'm lost on how to solve it.
 

Answers and Replies

  • #2
berkeman
Mentor
56,493
6,400
I've tried a whole manner of different things to try and solve this:

Prob.8-67.jpg


Determine the smallest force P needed to lift this 150kg cylinder.
Coefficients of static friction
At A: 0.7
At B: 0.3
At C: 0.4

I've tried different things and I'm lost on how to solve it.
Could you please show us your two FBDs and what equations you have written so far?
 
  • #3
634
1
Could you please show us your two FBDs and what equations you have written so far?
My scanner is giving me issues. It doesn't get along with Linux. I'll just describe them.

The drum has a normal and force of friction at point A At point B there is a normal that is at 80 degrees from the x axis, and different frictional force. It also has a weight force.

The wedge has the pushing force and the force of friction with respect to the ground on it. There is a force of friction at point B opposite to the direction on the drum, and a normal perpendicular to the top face. The problem didn't specify a mass for the wedge, so I decided to neglect it.

Normal Force At B:
FNB=150*9.8*sin(10)+Fp*sin(10)

Frictional Force At B:
FFB=0.3FNB

Normal Force At A:
I reasoned that the only thing pushing the cylinder into the wall would be it's own weight force pulling it down the wedge, and the horizontal component of the frictional force at point B

FNA= 150*9.8*sin(10)+FFBcos(10)

Frictional Force At A:
FFA=0.7FNA

Normal Force At C:
I think the only source would be the direct weight of the cylinder
FNC=150*9.8

Friction Between Wedge and Ground:
FFC=150*9.8*0.3
 

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