Question on a ball dropping( conservation of energy)

In summary, we calculated the kinetic energy and initial rebound velocity of a ball dropped from a height of 7m to a height of 4.5m, using the equations for gravitational potential energy and kinetic energy. The kinetic energy just before impact was found to be 70J, and the initial rebound velocity can be found using the same equations with the new height. However, there was a loss of kinetic energy on impact that was not accounted for in the calculations.
  • #1
Peter-John King
1
0

Homework Statement



A ball of mass 1 Kg is dropped from a height of 7m and rebounds to a height of 4.5m Calculate:
its kinetic energy just before impact
the initial rebound velocity of the ball and kinetic energy. Account for loss of kinetic energy on impact



2. Homework Equations [/B]
i am not sure of all the relevant equations i used pe=mgh and k.e=1/2mv^2

The Attempt at a Solution


I found the answer to a using the formula P.E.=mgh=1x10x7=70J
K.E.=P.E.=70J
I do not know how to find the second answer
 
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  • #2
Peter-John King said:
I found the answer to a using the formula P.E.=mgh=1x10x7=70J
K.E.=P.E.=70J
Good.

Peter-John King said:
I do not know how to find the second answer
Use the same equation. (A different height, of course.)
 

Related to Question on a ball dropping( conservation of energy)

1. How does the height of the ball affect its potential and kinetic energy?

According to the law of conservation of energy, the total energy of a system remains constant. This means that as the ball is dropped from a higher height, its potential energy decreases and its kinetic energy increases. Therefore, the higher the drop height, the greater the kinetic energy of the ball at impact.

2. Why does the ball bounce back to its original height after it hits the ground?

This is due to the conversion of kinetic energy into potential energy. As the ball falls and gains kinetic energy, it then loses that energy when it hits the ground and it is converted into potential energy. The potential energy then causes the ball to bounce back up to its original height.

3. Is friction a factor in the conservation of energy for a ball dropping?

Yes, friction is a factor that can affect the conservation of energy in a ball dropping. Friction acts against the motion of the ball, causing some of its kinetic energy to be converted into heat energy. However, the overall conservation of energy still applies.

4. How does the mass of the ball affect its energy during a drop?

The mass of the ball does not affect its potential or kinetic energy during a drop. According to the law of conservation of energy, the energy of a system is only dependent on its initial and final state, not on the mass of the object.

5. What other factors can affect the conservation of energy in a ball dropping?

Aside from friction, other factors that can affect the conservation of energy in a ball dropping include air resistance, the elasticity of the ball, and the surface it is dropped on. These factors can cause some energy to be lost or converted into other forms, but the total energy of the system remains constant.

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