Question

The c.g.s unit of work is
A. N
B. Dyne
C. erg
D. J

Answer 1

Hint: C.G.S is a system of standard units. C.G.S is an acronym of Centimeter-Gram-Second. The work in the C.G.S system can be defined as the amount of work done by a force of one dyne to move a distance of one cm. To find any unit in a specific system, the entire formula of the quantity has to change into the particular system of standard.

Complete step by step answer:
A work is said to be done only if the object is displaced in the direction of the force. The total work done can find out from the product of the applied force and the displacement.
The SI unit of work is the joule. 1 joule is the amount of work required to move an object by 1 metre by applying a force of 1 Newton.
Similarly, the erg is the unit of work in the CGS system. One erg is defined as the work done by a force of one dyne to move a distance of one cm.
\[\text{1 Joule}={{10}^{7}}\text{erg}\]
So, the correct option is C.

Additional information: The work done can be positive or negative according to the direction of force and displacement. If the applied force and the displacement are in the same direction, then the work is said to be positive. If the applied force and the displacement are in the opposite direction, then the work is said to be negative. If no displacement occurs due to the force, then we can say that there is no work done. The work done will be zero if we are applying a force perpendicular to the direction of the force.
\[W=F.d\], where W is the work done, F is the force applied and d is the displacement occurs.
According to dot product,
\[W=Fd\cos \theta \], where \[\theta \] is the angle between force direction and the displacement direction.
If the angle is \[90{}^\circ \] or its multiples, then the work done will be zero.

Note: Here the erg is not able to find out directly from the formula of work done. It is a different word, that you should learn yourself. It is not commonly used for our applications. You should remember this quantity to represent work in the CGS system. Most of the units can find out from the formula. But some of these units are represented in other names also.