A kite, the mass of which is 500 g, rises with a constant speed of air currents to a height of 80 m.

A kite, the mass of which is 500 g, rises with a constant speed of air currents to a height of 80 m. Determine the work of the force that lifted the kite. Acceleration of free fall is taken equal to 10 m / s2.

m = 500 g = 0.5 kg.

h = 80 m.

g = 10 m / s2.

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 of the body under the action of the force, ∠α is the angle between force F and displacement S.

Since the kite rises evenly, then, according to 1 Newton’s law, the lifting force F is equal to the force of gravity m * g: F = m * g.

S = h, ∠α = 0 °, cos0 ° = 1.

Work A of the lifting force of a flying kite will be determined by the formula: A = m * g * h.

A = 0.5 kg * 10 m / s2 * 80 m = 400 J.

Answer: the work of the force that lifted the snake is A = 400 J.