A factory worker pushes a 30.0 kg crate a distance of 3.7 m along a level floor at constant velocity by pushing downward at an angle of 30∘ below the horizontal. The coefficient of kinetic friction between the crate and floor is 0.25. Required:
a. What magnitude of force must the worker apply?
b. How much work is done on the crate by this force?
c. How much work is done on the crate by friction?
d. How much work is done on the crate by the normal force? By gravity?
e. What is the total work done on the crate?

a) , b) , c) , d) ; , e)

Explanation:

a) The net force exerted on the crate is:

The magnitud of the force that the work must apply to the crate is:

b) The work done on the crate due to the external force is:

c) The work done on the crate due to the external force is:

d) The work done on the crate due the normal force is zero, since such force is perpendicular to the motion direction.

And, the work done by gravity is:

e) Lastly, the total work done is:

magnified images possible images can be real = projected onto a screen