# Physics Questions and Answers – Introduction to Work, Energy and Power

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This set of Physics Multiple Choice Questions & Answers (MCQs) focuses on “Introduction to Work, Energy and Power”.

1. The energy possessed by a body by the virtue of its motion is called ______
a) Kinetic energy
b) Potential energy
c) Total energy
d) Motion energy

Explanation: The kinetic energy of a body emerges due to its motion. More specifically, the velocity of a body decides the amount of kinetic energy it has. Usually, the kinetic energy of a body with mass m is given as K.E. = $$\Big(\frac{1}{2}\Big)$$mv2, where v is the velocity of the body.

2. The energy possessed by a body by the virtue of its position is called ______
a) Kinetic energy
b) Potential energy
c) Total energy
d) Position energy

Explanation: The potential energy of a body emerges due to its position. More specifically, the displacement of a body from the reference position decides the amount of potential energy it has. Usually, the potential energy of a body with mass m is given as P.E.=mgh, where h is the height of the body from the ground plane and g is the acceleration due to gravity. Absolute potential of a body cannot be found. Only the relative value can be found out.

3. Energy is ________
a) Work
b) The ability to create work
c) Quantification of work
d) Force multiplied by displacement

Explanation: Energy is defined as the ability to create work. When a force is applied on a body to create displacement, work takes place. Work is quantified by the force applied by the displacement. Whereas the energy is the ability of the force to create work. In general, the total input energy = total output energy + work.

4. Power is ______
a) Rate of doing work
b) Ability to do work
c) Rate of energy creation
d) Equivalent to work

Explanation: Power is defined as the rate of doing work. The ability to do work is energy. Energy can neither be created nor be destroyed, hence, the rate of energy creation does not exist.

5. The unit of energy has been named after ______
a) James Prescott Joule
b) John Prescott Joule
c) Jammie Joule
d) Jessy Joule

Explanation: The SI unit of energy is Joule. It has been named after the famous scientist James Prescott Joule. He made a significant contribution to the word of science by discovering the relationship of energy with mechanical work.

6. In which category do potential and kinetic energy fall?
a) Mechanical energy
b) Electrical energy
c) magnetic energy
d) Usual energy

Explanation: Mechanical energy is composed of potential and kinetic energy. Potential energy is due to the position of the body. Kinetic energy is due to the motion of the body. Both when combined represent the total mechanical energy of the body.

7. How many Ergs are there in 1 Joule?
a) 10
b) 104
c) 107
d) 109

Explanation: Erg is the unit of energy in CGS system. One Joule = 107 ergs. This can be found out by putting in the CGS units in the expression for energy.

8. What is the correct expression for power?
a) P = dW/dt
b) P = F * d
c) P = E
d) P = dE/dt

Explanation: Power is defined as the rate of change of work. Hence, P = dW/dt. Instantaneous power = Force x instantaneous speed. Average power = total work / total time.

9. What is the correct expression for Work?
a) W = F * ds
b) W = P/t
c) W = E
d) W = E/t

Explanation: Work occurs when a force is applied on a body some displacement occurs as a result. Work is quantified as force multiplied by displacement. Hence, W = F * s. Instantaneous work is given as W = F * ds.

10. Energy involved in creating work _____
a) Gets used up
b) Gets transferred
c) Gets exhausted
d) Gets lost