Example:

A 5.0 kg block is pulled by a horizontal force of 50.0 N along a rough horizontal surface at a constant acceleration of 6.0 m/s/s. What is the coefficient of kinetic friction?

m = ?

m = 5.0 kg

F_T = ?

F_T = 50.0 N

a_x = ?

a_x = 6.0 m/s²

a_y = ?

a_y = 0.00 m/s²

F_g = m g

F_g = (5.0 kg) (-9.8 m/s²)

F_g = - 49 N

F_{net y} = m a_y

F_{net y} = (5.0 kg) (0.00 m/s²)

F_{net y} = 0.00 N

F_{net y} = F_g + F_N

0.00 N = - 49 N + F_N

F_N = 49 N

F_{net x} = m a_x

F_{net x} = (5.0 kg) (6.0 m/s²)

F_{net x} = 3.0 x 10¹ N

F_{net x} = F_f + F_T

3.0 x 10¹ N = F_f + 50.0 N

F_f = -2.0 x 10¹ N

|F_f|= F_N

2.0 x 10¹ N = 49 N

= 0.41