Answer:
22 N
Explanation:
The box is moving, so there is kinetic friction.
The speed is constant, so there is no acceleration.
Draw a free body diagram of the box. There are four forces.
Normal force Fn pushing up.
Weigh force mg pulling down.
Applied force F pushing right.
Friction force Fn μk pushing left.
Sum the forces in the y direction:
∑F = ma
Fn − mg = 0
Fn = mg
Sum the forces in the x direction:
∑F = ma
F − Fn μk = 0
F = Fn μk
F = mg μk
F = (11.2 kg) (9.8 m/s²) (0.200)
F = 22.0 N
