Homework SourseA father pulls his two kids on a sled with a force of T 100
A father pulls his two kids on a sled with a force of T = 100 lb at an angle of 0. The combined weight of the sled and children is equal to 100 lb. What angle(s) does the father have to pull at for the sled to accelerate at 25 ft/s^2? Take the coefficient of kinetic friction for waxed wood on dry snow to be 0.4. 
Solution
Net force along x axis is,
100*a*cos(theta)= mu* RN
100*25 ft/s2 (cos (theta))=(0.4)(100*32.174 ft/s2)
Here g= 32.174 ft/s2
Therefore
theta=59 degrees
