an engine block of mass 275kg rest on a plane which is inclined at 13 degrees to the horizontal.if the plane can be tilted to a maximum angle of 21 degrees before the engine block slide due to its weight.calculate the minimum force parallel to the plane required to move the engine block up at constant speed.

Question

an engine block of mass 275kg rest on a plane which is inclined at 13 degrees to the horizontal.if the plane can be tilted to a maximum angle of 21 degrees before the engine block slide due to its weight.calculate the minimum force parallel to the plane required to move the engine block up at constant speed.

Answer 1

Consider the weight of the engine:

portion of weight down the plane: mgsinTheta
portion of weight normal to the plane:
mgCosTheta

WEll, at 21 degrees, the friction = the weight down plane
mu*mg*cosTheta=mgSinTheta
solve for mu.

Now, at 21degrees, it starts to slide down. It would require this force to move it up the plane: (remember friction is now down the plane)
Force=weight down plane+ friction
= mgSinTheta+mu*mgCosTheta