• Post a New Question
• Current Questions
• Chat With Live Tutors

Homework Help: Physics

Posted by Elaine Jetton on Sunday, September 18, 2011 at 9:01pm.

A 1200-N crate is being pushed across a level floor at a constant speed by a force of 260 N at an angle of 20.0° below the horizontal.
(a) What is the coefficient of kinetic friction between the crate and the floor?
(b) If the 260 N force is instead pulling the block at an angle of 20.0° above the horizontal as shown in the figure, what will be the acceleration of the crate? Assume that the coefficient of friction is the same as that found in part (a).
For (a) I got .489, which is wrong. Since I cannot figure out (a) I cannot figure out (b).

• Physics - drwls, Sunday, September 18, 2011 at 9:13pm

  For (a), the kinetic friction coefficient Uk, you need to divide the motion-producing force component by the total force normal to the plane
  Uk = 260cos20/(1200 + 260 sin20)
  = 0.1896
  

• Physics - Elaine Jetton, Sunday, September 18, 2011 at 9:42pm

  whats the equation I should use for (b) because I'm getting the wrong answer.
  

• Physics - drwls, Sunday, September 18, 2011 at 10:03pm

  (b) The motion-producing force component remains 260cos20, but the normal component applied to the floor becomes 1200 -260sin20.
  
  Then compute the net force along the direction of motion:
  260cos20 - 0.1896*(1200 -260sin20)
  
  Divide that by the mass (1200/g)to get the accleration.
  

• Physics - Anonymous, Sunday, March 10, 2013 at 3:05pm

  .138
  

Answer this Question

First Name:
School Subject:
Answer:

Related Questions

physics - A 1,440-N crate is being pushed across a level floor at a constant ...
physics - A 1,040-N crate is being pushed across a level floor at a constant ...
physics - A 1100 N crate is being pushed across a level floor at a constant ...
physical aspects of nature - A 1,440-N crate is being pushed across a level ...
physics - A 1,080-N crate is being pushed across a level floor at a constant ...
physics - A 1,440-N crate is being pushed across a level floor at a constant ...
Physics - Sally applies a horizontal force of 500 N with a rope to dtag a wooden...
Physics - A 800 N crate is being pulled across a level floor by a force F of 320...
Physics - A 1060 N crate is being pulled across a level floor by a force F of ...
Physics - A crate is initially at rest on a rough, horizontal floor. The crate ...

For Further Reading