7CQ - College Physics (Urone)

Question

Identify the type of energy transferred to your body in each of the following as either internal energy, heat transfer, or doing work: (a) basking in sunlight; (b) eating food; (c) riding an elevator to a higher floor

Step-by-Step Solution

Answer

• In basking of sunlight, heat gets transferred from the sun to the body. Hence it is Heat transfer energy.
• Eating food in return gives us energy. This energy is stored in our body which is known as Internal Energy.
• The name riding an elevator means doing work. There is an increase in the potential energy against the gravity which makes the body move upwards. Hence the energy is Work Done.

Step 1 (a): Basking in Sunlight

• The technique through which heat is transferred from sun to the body is called as radiation.
•  The Electromagnetic waves of various wavelengths which also includes the visible light, radiation causes the energy to transmit.
• No medium is necessary for the energy to be transferred.

Step 2 (b): Eating Food

• Eating food increases the potential energy of our body which in turn increases the internal energy.
• Our body takes food as input and releases energy as output by the process of burning the calories
• This internal energy comprises of work done, heat transfer, etc. Rest of the amount of the energy goes to the storage known as fats. 

Step 3 (c): Riding an Elevator

• The elevator has \({\rm{3}}\) forces i.e., the force of gravity, upward force and downward force. 
• As the lift moves in the upward direction, the person’s body also moves upwards and here the force is in parallel with the person’s body. It is represented as; \({\rm{N}}\;{\rm{ = }}\;{\rm{mg}}\;{\rm{ + ma}}\) Where \({\rm{N}}\) stands for Normal Force, \({\rm{m}}\) stands for Mass, \({\rm{g}}\) stands for gravitational force and \({\rm{a}}\)stands for acceleration.
• The weight of our body moves downwards against the force of gravity. The energy drained in this process converts into potential energy which in turn increases while moving upwards.