A ball weighing 500 g was thrown vertically upwards what kind of work will the force of gravity do when

A ball weighing 500 g was thrown vertically upwards what kind of work will the force of gravity do when it rises to a height of 80 cm.

m = 500 g = 0.5 kg.

g = 9.8 m / s2.

h = 80 cm = 0.8 m.

∠α = 180 °.

A -?

The formula for determining the mechanical work A is: A = F * S * cosα, where F is the force that acts on the body, S is the movement of the body under the action of the force F, ∠α is the angle between the direction of action of the force F and the movement of the body S.

The force of gravity F is always directed vertically downward and is determined by the formula: F = m * g.

The movement of the body S directed vertically upwards and will be equal to the height of the rise h: S = h.

Since the force of gravity m * g is directed vertically downward, and the displacement S is vertically upward, the angle between them is ∠α = 180 °, cos180 ° = -1.

A = – m * g * h.

A = – 0.5 kg * 9.8 m / s2 * 0.8 m = – 3.92 J.

Answer: when lifting the ball, gravity will do the work A = – 3.92 J.