Physics question for newtons laws.

Question

you are helping a friend move a fridge. You apply a horizontal force of 276N in the positive x direction to try and move the 58 kg fridge. The coefficient of static friction between the refrigerator and the floor is .70

A) draw the free body diagram of the refrigerator . Name symbollically and describe the direction of the forces acting on the fridge.

B) how much static frictional force does the floor exert on the refrigerator.give both magnitude and direction.

C) What maximum force do you need to apply before the fridge starts to move?

D) explain why the answers for B and C differ.

Answer 1

The forces acting on the refrigerator:

Fg = force of gravity = mass * g, where g = 9.81m/sec^2

"reaction force"--the floor pushing up on the refrigerator = Fg

Ff = friction force

Fa = applied force

All the forces here are either vertical or horizontal---no angles to deal with.

The friction force is simply the product of the gravity force (vertical) and the coefficient of friction.

Because it is static friction, you have to push with a force greater than the friction force--for the object to start moving (I think this is the answer to question D