Answer:
33.72N
Explanation:
To find the magnitude of the friction force you take into account all forces over the object:
(1)
where Mgsin0 is the gravitational force, Ff is the friction force F is the force of the worker, m is the mass and a is the acceleration of the object while it is going up the ramp.
it is necessary to find the acceleration of the crate:
with this value and the values for m, g, the angle and d you obtain, by using (1) you obtain:
(3)
For the calculation of F:
If the surface would be frictionless you have:
with these values you can calculate the force F:
BY replacing this values in the expression (3) you get:
hence, the magnitude of the friction force is 33.72N