With uniform lifting of the load to a height of h = 40cm, work A = 16kJ was performed. Determine the mass of the cargo.

h = 40 cm = 0.4 m.

A = 16 kJ = 16000 J.

g = 10 m / s2.

m -?

The work of force A is determined by the formula: A = F * S * cosα, where F is the force that lifts the load, S is the movement of the load, ∠α is the angle between the direction of action of the force F and displacement S.

The movement of the body S will be equal to the height of the lift of the body h: S = h.

Since the force is directed vertically upward and the body moves vertically upward, then ∠α = 0 °, cos0 ° = 1.

Since the load is lifted uniformly in a straight line, then according to 1 Newton’s law, the force F, which lifts the load, is balanced by the force of gravity m * g: F = m * g.

A = m * g * h.

m = A / g * h.

m = 16000 J / 10 m / s2 * 0.4 m = 4000 kg = 4 t.

Answer: the mass of the cargo is m = 4 tons.