Test: Work, Energy and Power - UPSC MCQ

Energy involved in creating work gets transferred or converted into some other kind of energy. Energy can neither be created nor be destroyed. Hence, the energy involved will get converted into some other form of energy. Usually in mechanical work, the energy gets dissipated as heat energy.

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.

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.

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.

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.

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. = (1/2)mv², where v is the velocity of the body.

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.

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.

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.

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.