A fireman of mass 80 kg slides down a pole. When he reaches...

A fireman of mass $80 \mathrm{kg}$ slides down a pole. When he reaches the bottom, $4.2 \mathrm{m}$ below his starting point, his speed is $2.2 \mathrm{m} / \mathrm{s}$. By how much has thermal energy increased during his slide?

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Key Concepts

Energy Transformation and Friction

During motion involving friction, some of the mechanical energy is converted into thermal energy. The difference between the decrease in gravitational potential energy and the gain in kinetic energy is accounted for by the increase in thermal energy due to friction.

Kinetic Energy

Kinetic energy is the energy that an object possesses due to its motion. It is proportional to the mass of the object and the square of its velocity. An increase in an object's kinetic energy during motion indicates that some of its potential energy has been converted into kinetic form.

Conservation of Energy

This principle states that the total energy in a closed system remains constant. In mechanics, when non-conservative forces like friction are present, the mechanical energy (potential plus kinetic) is not conserved; instead, some energy is transformed into other forms, such as thermal energy.

Gravitational Potential Energy

Gravitational potential energy represents the energy possessed by an object due to its position in a gravitational field. It is calculated as the product of mass, gravitational acceleration, and height. When an object descends, its gravitational potential energy decreases.

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