A boy (60 kg) is pushing a sled (5 kg) with a stick, so that the stick makes a 30˚ angle with the vertical. He applies a force of 20 N, so that the force acts along the stick (i.e., there is no shear or friction force). There is negligible friction between the sled and the ground. At time t = 0 s, the sled is at rest.
What is the normal force of the ground on the sled?