Answer:
4.8 m/s²
Explanation:
Draw a free body diagram of the truck. There are three forces:
Weight force mg pulling down
Normal force Fn pushing perpendicular to the hill
Friction Force Fn μ pushing up the hill
Sum of the forces in the perpendicular direction:
∑F = ma
Fn − mg cos θ = 0
Fn = mg cos θ
Sum of the forces in the parallel direction (taking down the hill to be positive):
∑F = ma
mg sin θ − Fn μ = ma
mg sin θ − mg μ cos θ = ma
g sin θ − g μ cos θ = a
a = g (sin θ − μ cos θ)
Substitute:
a = (9.8) (sin 40° − 0.2 cos 40°)
a = 4.8 m/s²
