(a) -267 N
Explanation: if the refrigerator is not moving, it means that the net force acting on it is zero.
We are only interested in the motion along the horizontal direction; there are two forces acting in this direction:
- The pushing force, forward, F=+267 N
- The static frictional force, backward,
Since the net force must be zero, we have
(b) 363.1 N
The largest pushing force that can be applied to the refrigeratore before it begins to move is equal to the magnitude of the maximum static frictional force, which is given by:
where
is the coefficient of static friction
m = 57 kg is the mass of the refrigerator
g = 9.8 m/s^2 is the gravitational acceleration
Substituting,