The work done by a person in carrying a box of mass 15 kg through a vertical height of 5 m is 5000 J. The mass of the person is _______ Take g = 10 m/s²

Concept:

• Potential energy is defined as the energy stored due to change in position relative to others, stresses within itself, or many factors.
  • The potential energy (U) = m g h [where m= mass of body, g= acceleration due to gravity, h = distance from the ground].
  • If the height of a body increases from the ground its energy also increases and vice versa.

Calculation:

Work-done to carry a box up to height = m g h

Here the person himself do work on his own mass + mass of box

Let the mass of the person be x

So,

Work-done by potential energy = mass (both) × g × height

⇒ 5000 J = (x kg + 15 kg) × 10 × 5

⇒ 5000 = (x+15) × 50

⇒ 100 = x + 15

⇒ x = 85 kg

Hence the mass of the person is 85 kg.