An object with a mass of 5 kg5kg is on a ramp at an incline of pi/12 π12. If the object is being pushed up the ramp with a force of 2 N2N, what is the minimum coefficient of static friction needed for the object to remain put?

1 Answer
Apr 21, 2016

Lets consider the total force on the object:

  1. 2N2N up the slant.
  2. mgsin(pi/12) ~~ 12.68 Nmgsin(π12)12.68N downwards.

Hence the total force is 10.68N10.68N downwards.

Now the force of friction is given as mumgcosthetaμmgcosθ which in this case simplifies to ~47.33mu N~47.33μN

so mu = 10.68/47.33 ~~ 0.23μ=10.6847.330.23

Note, had there not been the extra force, mu = tanthetaμ=tanθ