Question

Define 1J of work?

Answer 1

Hint: Let us first understand what is meant by work. Work is the measure of energy that occurs when an external force is applied on an object and it moves along the direction of applied force. It is represented as the product of displacement and force. The S.I unit of work is Joule.

Complete step by step answer:
One joule of work is said to be done when one newton of force is applied on an object that causes a displacement of one meter along the direction of force. In electrical terms, one joule is the energy released when one ampere current is passed through a resistance of one ohm in one second. Here one joule is equal to one watt-second. The S.I unit of work, joule is named after physicist James Prescott Joule.

Additional information:
According to the work energy theorem, work done is equal to kinetic energy.
Proof:
We know that work done is the product of force and displacement.
\[W = F \times d\] -(1)
According to Newton’s formula of force;
$F = m \times a$
Displacement of the particle is given by the formula,
$
{{v_f}^2} = {{v_i}^2 } + 2ad \\
\Rightarrow d = \dfrac{{{{v_f}^2} - {{v_i}^2}}}{{2a}} \\$
Substituting for F and d in -(1) we have,
$
W = ma \times \dfrac{{{{v_f}^2} -{{v_i}^2}}}{{2a}} \\
\Rightarrow W = \dfrac{1}{2}m{{v_f}^2} - \dfrac{1}{2}m{{v_i}^2} \\
$
Kinetic energy is given by,
$KE = \dfrac{1}{2}m{v^2}$
Therefore,
$
W = K{E_f} - K{E_i} \\
\Rightarrow W = \Delta KE $

Note:Alike kinetic energy, work done is the same thing as potential energy. The difference is that in a system of potential energy state, the energy is stored as the virtue of its motion. As a unit of energy, work is also defined as the quantity of energy needed to raise the temperature of one kilogram of water by one degree Celsius.