Answer:
D. 10 N
Explanation:
Draw a free body diagram of the box. There are four forces:
Normal force N pushing up.
Weight force mg pulling down.
Applied force P to the right.
Friction force Nμ to the left.
Sum of forces in the y direction:
∑F = ma
N − mg = 0
N = mg
Sum of forces in the x direction:
∑F = P − Nμ
∑F = P − mgμ
∑F = (50 N) − (9 kg) (9.8 m/s²) (0.45)
∑F ≈ 10 N
