Physics -- check answers please
posted by Liz .
Use g=10 N/kg in this assignment.
1. What is the gravitational energy (relative to the unstretched surface of the trampoline) of the 20 kg ball at its apex 2 m above the trampoline?
I got 400 J
2. What is the kinetic energy of the ball just before impacting the trampoline?
I got 0 J
3. At maximum stretch at the bottom of the motion, what is the sum of the elastic and gravitational energy of the ball?
Is it because the sum of elastic and potential energy is equal to the change in gravitational energy from original position?
4. What conclusions can be drawn from the answers above
I'm not too sure what to put as my answer
1. ok m g h = 20 * 10 * 2 Joules
2. No. That 400 Joules of potential energy becomes 400 Joules of kinetic energy during the fall.
3. Yes - At maximum stretch the ball stops. The ball is now 2 meters plus x below the starting point where x is the stretch distance down. The total energy is all potential in the springs and gravitational and is m g (2 + x)
4. Energy is conserved I suppose.