The tower crane lifts in a horizontal position a steel girder weighing 400 kg to a height

The tower crane lifts in a horizontal position a steel girder weighing 400 kg to a height of 12 meters. What is the useful work of the crane?

Initial data: m (weight of a steel beam) = 400 kg; h (the height to which the tower crane lifted the beam) = 12 m.

Constants: g (acceleration due to gravity) = 10 m / s ^ 2.

The useful work of a tower crane can be calculated as the product of the force acting on the beam and its displacement, or as a change in the potential energy of the beam:

A = Ft * s = m * g * h = En2 – En1 = En.

Let’s do the calculation:

A = 400 * 10 * 12 = 48000 J = 48 kJ.

Answer: The tower crane performs 48 kJ useful work.