The problem involves calculating the horizontal force required to pull a sled with additional weight at a constant velocity on a horizontal surface. The sled initially weighs 12 kg, and the scenario changes with two girls, each weighing 57 kg, sitting in it.
The discussion includes various calculations and interpretations of forces acting on the sled. Some participants offer guidance on how to approach the problem, while others question the accuracy of the results and the assumptions made regarding friction and mass.
Participants are working under the assumption that the sled moves at a constant velocity, which implies that the net force is zero. There is also a focus on the coefficient of friction and how it relates to the forces involved.
New mass is 126kg.whozum said:Total mass = 12kg
Force of Gravity = 12x9.8 = 117.6N
Normal force = -Fg = -117.6N
Net vertical Force = Force of Gravity + Normal force = 117.6 + (-117.6) = 0N
Net Horizontal Force = Pull force + Friction force = 11N + (mu_k)*N = 0N since velocity is constant, there is no acceleration.
11 - mu_k*117.6 = 0
-1136mu_k = -11
mu_k = -11/-117.6 = 0.1
New mass is 12+2x57 = 116kg
Gravity Force = - Normal force = 1136.8N
Fy = 0
Fx = Pull force + Friction Force = 0
Friction force = mu_k * N = 113.7N
Pull force + 113.7 = 0
Pull force = -113.7N.
The negative sign just means its in the opposite direction of the friction force.