
Spencer G. answered 10/15/21
Mechanical Engineering Graduate Student
Starting with the x and y components of tensional force:
F_Tx = F_T * cos(theta) = 50 * cos(25) = 45.3154 N
F_Ty = F_T * sin(theta) = 50 * sin(25) = 21.1309 N
Finding force of gravity F_g:
F_g = m*g = (20 kg) * (9.81 m/s^2) = 196.2 N
Solving for normal force F_N with zero acceleration:
Sum F_y = 0 = F_N + F_Ty - F_g
F_N = F_g - F_Ty = (196.2 N) - (21.1309 N)
F_N = 175.069 N
Solving for frictional force F_f with zero acceleration:
Sum F_x = 0 = F_Tx - F_f
F_f = F_Tx
F_f = 45.3154 N
Solving for work done:
W_T = F_Tx * D_x = (45.3154 N) * (12 m) = 543.785 J
W_g = F_g * D_y = (196.2 N) * (0 m) = 0 J
W_N = F_N * D_y = (175.069 N) * (0 m) = 0 J
W_f = F_f * D_x = (-45.3154 N) * (12 m) = -543.785 J
Finding coefficient of friction:
F_f = mu * F_N
mu = F_f / F_N = (45.3154 N) / (175.069 N)
mu = 0.258843