Question

A force of 300N is required just to move a box up an inclined plane of angle 15". The force is acting
parallel to the plane. But if the inclination of the plane is made 20, a 350 N force. parallel to the inclined plane is required to just move it up. Determine weight of the box and coefficient of static friction​

Answer 1

Answer:

Case-1 Consider When the slope of the plane be 15º Sum of forces parallel to plane = 0 P – µR – W sin 15° = 0 ...(i) Sum of forces perpendicular to plane = 0 R = W cos 15° ...(ii) Putting the value of (ii) in (i), We get P = µ W cos 15° + W sin 15° = 0 200 = 0.96µW + 0.25W ...(iii) Case-2 Consider When the slope of the plane be 20º Sum of forces parallel to plane = 0 P – µR – W sin 20° = 0 ...(iv) Sum of forces perpendicular to plane = 0 R = W cos 20° ...(v) Putting the value of (v) in (iv), We get P = µW cos 20° + W sin 20° = 0 250 = 0.939µW + 0.34W ...(vi) Solved equation (iii) and (vi) we get

W = 623.6N and µ = 0.06