What pressure will be exerted by a 20 N box that has equal sides of 1 meter

Two cars collide, lock bumpers and move together after the collision.this collision is known as perfectly inelastic collision.

The answer is 4f======since electrostatic force is given by    we let f be the electrostatic force when  r = 1 m    if we let  denote the electrostatic force when the distance is decreased so that r = 0.5m, then    we established earlier that f = kq₁q₂. therefore    the force will now be 4f.

The answer is b. all other properties are crucial.