# The length of the ice mountain is 20 m and the height is 4 m. What work must be done to lift a sled

**The length of the ice mountain is 20 m and the height is 4 m. What work must be done to lift a sled weighing 15 kg on this mountain? how much force is required to lift the sled?**

S = 20 m.

h = 4 m.

m = 15 kg.

g = 9.8 m / s2.

A -?

F -?

According to the definition, mechanical work A is determined by the formula: A = F * S * cosα, where F is the force with which the sleigh is pulled, S is the movement of the sleigh, ∠α is the angle between the force F and the displacement S. Since the force F acts along the inclined plane, then ∠α = 0 °, cos0 ° = 1. A = F * S.

We will assume that the sleigh is raised evenly, then, according to Newton’s 1 law, the action of forces on it is compensated.

m * g + N + F = 0 – vector.

OH: – m * g * sinβ + F = 0.

OU: – m * g * cosβ + N = 0.

F = m * g * sinβ.

sinβ = h / S.

F = m * g * h / S.

F = 15 kg * 9.8 m / s2 * 4 m / 20 m = 29.4 N.

A = 29.4 N * 20 m = 588 J.

Answer: to lift the sleigh on the icy mountain, force F = 29.4 N is required, work is performed A = 588 J.