140 a) A man tries to pull a rigid wall
for a long time but fails to displace it.
Wist is the external work done by
hin:
b) Suggest two conditions for the
work done by a force to be zero.
Ans:
Answers
Answer:
As we know work done us Force X Displacement
If a person tries to push the wall he applies the force but displacement is zero, so product of force and displacement will be zero. So work done is zero.The correct answer is "no work done".
Explanation:
The expression for the work done is as follows;
W= Fs
Here, F is the applied force and s is the displacement.
The work is to be done when the applied force on the object displaces it to some distance.
The work done is negative when the body displaces in an opposite direction to the applied force.
The work done is positive when the body displaces in the same direction to the applied force.
In the given problem, a man pushes a wall and fails to displace it. He does not do any work as the wall is not displaced in this case.
Therefore, the work done in this case is zero.