Answer:
- 2.7 x 10^-6 J
Explanation:
q1 = 1 nC at x = 0 cm
q2 = - 1 nC at x = 1 cm
q3 = 4 nC at x = 2 cm
The formula for the potential energy between the two charges is given by

where r be the distance between the two charges
By use of superposition principle, the total energy of the system is given by



U = - 2.7 x 10^-6 J
Dropping a bouncy ball and stretching a rubber ban.
When you set a heavy bag down on the ground, you are doing negative work on it.
I think the answer is convection