Respuesta :

Answer:

Explanation:

Force - frictional Force = m * a

20N - 5N = 5 * a

15N = 5*a

15N / 5 = a

a = 3 m/s^2

You should note a couple of things.

1. The frictional Force always opposes the direction of motion. In this case it is minus and the 20 N is plus. It makes the acceleration less. If the friction force was not there then 20 N = m * a

20N = 5 kg * a

a = 20/5

a = 4 m/s^2.