In tug of war, the team that exerts a larger tangential force on the ground wins. Consider the period in which a team is dragging the opposite team by applying a larger tangential force on the ground. List which of the following works are positive, which are negative and which are zero?

(a) work by the winning team on the losing team

(b) work by the losing team on the winning team

(c) work by the ground on the winning team

(d) work by the ground on the losing team

(e) total external work on the two teams.

#### Solution

(a) Work by the winning team on the losing team is positive, as the displacement of the losing team is along the force applied by the winning team.

(b) Work by the losing team on the winning team is negative, as the displacement of the winning team is opposite to the force applied by losing team.

(c) Work by the ground on the winning team is positive.

(d) Work by the ground on the losing team is negative.

(e) Total external work on the two teams is positive.