Determine the total work of forces that will be performed if a force equal to 3 N lifts a weight of 100 g to a height of 5 m.

F = 3 N.

g = 9.8 m / s ^ 2.

m = 100 g = 0.1 kg.

h = 5 m.

A -?

The work of force A is determined by the formula: A = F * S * cosα, where F is the force that acts on the body, S is the displacement under the action of the force, ∠α is the angle between force F and displacement S.

Two forces act on the body: gravity m * g, directed vertically downward, and the tension force of the rope F, for which the load is lifted, directed vertically upward.

The work of gravity: At = m * g * h * cos180 ° = 0.1 kg * 9.8 m / s ^ 2 * (- 1) = – 0.98 J.

The work of the rope pulling force: An = m * g * h * cos0 ° = 0.1 kg * 9.8 m / s ^ 2 = 0.98 J.

A = At ​​+ An.

A = 0.98 J – 0.98 J = 0.

Answer: the total work of forces is equal to 0: A = 0.