Answer:
0.168
Explanation:
According to Newton's second law, the net force on an object is equal to its mass times its acceleration. Drawing a free body diagram, there are 4 forces on the box: weight force mg pulling down, normal force N pushing up, friction force Nμ pushing left, and applied force F pulling up 23.5° above the horizontal.
Sum of forces in the y direction:
∑F = ma
F sin θ + N − mg = 0
N = mg − F sin θ
Sum of forces in the x direction:
∑F = ma
F cos θ − Nμ = 0
Nμ = F cos θ
μ = F cos θ / N
Substitute:
μ = F cos θ / (mg − F sin θ)
Plug in values and solve:
μ = 17.4 cos 23.5 / (10.4 × 9.8 − 17.4 sin 23.5)
μ = 0.168
