Question

A car trunk lies on a horizontal rough floor. The coefficient of friction between the truck and the floor is 0.4330.calculate the magnitude of the force p which is necessary to pull the truck horizontally if the force is applied a. Horizontally b.At 30°above the horizontal

Answer 1

Given:

μ = 0.433

α = 30°

m

Find: P_a, P_b

a)

$f_{k_x} + mg_x + N_x + P_x = 0\\ P = \mu mg = 0.433\ *\ 10m/s^2 \ *\ m\ kg =\ 4.33m\ N$

b)

$f_{k_x} + mg_x + N_x + P_x = 0\\ \mu mg = Pcos\alpha\\ P = \dfrac{\mu mg}{cos\alpha} = \dfrac{0.433 * 10m/s^2\ *\ m\ kg}{cos 30\degree} \approx 5m\ N$

Answer: a) P_a=4.33m N b) P_b=5m N

(where m is the mass of a truck in kilos)