ball hits the ground with 5 Joules of kinetic energy. It bounces and at the top of its first bounce it has 2 joules of gravitat ork did the floor do on the ball? -7Joules -3Joules 7 Joules 3 Joules

To solve this problem, we need to use the principle of conservation of energy. The total mechanical energy of the ball before it hits the ground is equal to the total mechanical energy of the ball after it bounces.<br /><br />Given information:<br />- The ball hits the ground with 5 Joules of kinetic energy.<br />- At the top of its first bounce, the ball has 2 Joules of gravitational potential energy.<br /><br />Let's denote the work done by the floor on the ball as W.<br /><br />The total mechanical energy of the ball before it hits the ground is:<br />Total mechanical energy = Kinetic energy + Gravitational potential energy<br />Total mechanical energy = 5 Joules + 0 Joules = 5 Joules<br /><br />The total mechanical energy of the ball at the top of its first bounce is:<br />Total mechanical energy = Kinetic energy + Gravitational potential energy<br />Total mechanical energy = 0 Joules + 2 Joules = 2 Joules<br /><br />According to the principle of conservation of energy, the total mechanical energy of the ball before it hits the ground is equal to the total mechanical energy of the ball at the top of its first bounce.<br /><br />Therefore, we can write the equation:<br />5 Joules = 2 Joules + W<br /><br />Solving for W, we get:<br />W = 5 Joules - 2 Joules = 3 Joules<br /><br />Therefore, the work done by the floor on the ball is 3 Joules.<br /><br />The correct answer is 3 Joules.