Physics help please

Question

A 4.0-kg block being pulled across a table by a horizontal force of 70 N also experiences a frictional force of 15 N. What is the acceleration of the block?

Answer 1

Hello Maya,

The net force is the vector (incorporating both the magnitude and direction) sum of all described forces. Since the forces are exerted in the exact opposite direction of each other, the magnitudes of the forces are subtracted from each other:

F_net = 70 N - 15 N = 55 N

Then, to find the acceleration, use:

F = ma

55 = 4.0 * a

a = 13.75 N (or 14 N if rounding to the correct number of significant digits)