Question

No work is done when:
A. A nail is hammered into the wooden box
B. A box is pushed along a horizontal floor
C. There is no component of force, parallel to the direction of motion
D. None of these

Answer 1

Hint: In this question we have been asked to determine the condition when the work is done is zero. We have been given conditions in the options, we have to select a proper statement among the given, that satisfies the condition that no work is done. We shall first discuss how work is done. We shall use the equation of work done due to force and apply the given condition and verify our answer.
Formula used:- \[W=F.d\cos \theta \]
Where,
W is the work done
F is the force applied
d is the displacement
\[\theta \] is the angle between the displacement vector and force

Complete step-by-step solution
We know that work done is given as the product of force and displacement in the direction of motion.
The equation of work done is given by,
\[W=F.d\cos \theta \]
Now, we have been asked that the work done for a system should be zero.
Now, from the above equation, we can say that if the work is done has to be zero, then any of the three conditions below can satisfy.
The work done will be zero if: 1) there is no net force on the body. 2) the displacement due to the force is zero. 3) \[\cos \theta =0\] which means that the angle between the force and displacement vector is zero. This is possible when there is no component of force acting parallel to the direction of motion or displacement.
Therefore, the correct answer is option C.

Note: When a body is moved from one place to another or is displaced to another point from its original position, by applying force we can say that work is done in such case. Work done is defined as the measurement of energy transfer when a force is applied to displace a body. Therefore, we can say that the energy transferred is equal to the work done.