Question

A stationary 15 kg object is located in a table near the surface of the earth. The coefficient of static friction between the surfaces is 0.40 and the coefficient of kinetic friction is 0.25.
A horizontal force of 20 N is applied to the object.
Determine the acceleration of the object.

Answer 1

maximum static friction acting on the object will be

$F_s = \mu_s mg$

plug in all values

$F_s = 0.40 \times 15 \times 9.8 = 58.8 N$

So here it means that if applied force is less than or equal to 58.8 N then the object will remain stationary as friction can balance the external force upto this limit of external force

So here it is given that applied force is 20 N

so here object will not move due to this force and it will remain at rest always

due to this applied force