Question

In a tug of war, the team that exerts a larger tangential force on the ground wins, the winning team not moving. Consider a period in which a team is dragging the opposite team by applying a larger tangential force on the ground. Which of the following work is negative?
A) Work by the ground on the winning team
B) Work done by the string on the winning team
C) Work by ground on the losing team
D) Total external work on the two teams

Answer 1

Work is the product of force and displacement. Work done is positive when the displacement is in the direction of the force applied. The work done is negative if the displacement is opposite to the direction of the applied force. If there is no displacement then the work is assumed to be zero.

Complete step by step solution:
In the question, it is mentioned that the winning team is not moving. This means that the displacement of the winning team is zero. When there is no displacement we consider the work done to be zero. Hence we can say that the first option is wrong.
The string by itself is not exerting any force on the teams. Hence we can rule out the second option also.
The losing team will move towards the winning team. That means they will have a displacement in the direction of the winning team. But the frictional force offered by the ground will be in the opposite direction to the displacement of the team. Since the displacement is in the opposite direction to the force applied, the work done will be negative. Therefore we can conclude that option C is the correct answer.

The answer is: Option (C), Work by ground on the losing team.

Note: Work done is calculated by multiplying force and displacement. Understanding the direction of force and displacement in each situation is very important in solving analytical problems. Force and displacement are both vector quantities but work is a scalar quantity it has only magnitude. Work transfers energy from one place to another or from one form to another.