Answer to Question #277866 in Physics for Var

Question

A block of mass m = 12 Kg is pushed at a constant speed, up an incline plane (angle of

inclination 30o

) though a distance of s= 4.5m and raised to a height h= 2m. The coefficient

of kinetic friction between the block and the incline is 0.41. Calculate the work done by

(a) Normal force

(b) the external force applied parallel to the incline.

(c) gravity

(d) the frictional force.

Answer 1

Work done by the

(a) Normal force:

$$W=hN=hmg\cos\theta=204\text{ J}.$$

(b) the external force applied parallel to the incline:

$$W=sF=s\mu mg\cos\theta=188\text{ J}.$$

(c) Gravity:

$$W=mgh=235\text{ J}.$$

(d) The frictional force:

$$W=sf=s\mu mg\cos\theta=188\text{ J}.$$