A 5 kg block is pushed across a table by a horizontal force of 40 N with an acceleration of 5 m/s^2. What is the frictional force opposing the motion?

15

Explanation:

mass, M = 5Kg

horizontal force, F_h = 40N

acceleration, a = 5 m/s^2

frictional force, F_f = ?

net force = ma

net force = F_h - F_f = 40N - F_f

40 - F_f = 5 x 5

- F_f = 25 - 40

multiply both side by - 1

F_f = 40 - 25 = 15

the frictional force is 15N