Question

A steady 45 N horizontal force is applied to a 15 kg object a table. The object slides against a friction force of 30 N. Calculate the acceleration of the object in m/s.

Answer 1

The net force on an object subject to friction is equal to the sum of the applied force and the frictional force.

Mathematically,

$F_{N} = ma = F_{applied} - f_{fr}$

Here, m is mass of object and a is its acceleration. We take frictional force negative because it opposes the motion of object.

Given, $m=15\ kg$ , $F_{applied} =45\ N$ and $f_{fr} = 30\ N$

Substituting these values in above formula, we get

$15\ kg\times a = 45\ N -30\ N=15\ N \\\\a=\frac{15\ N}{15\ kg} =1\ m/s^2$.

Thus, the acceleration of an object is $1\ m/s^2.$