Ametal ball with a mass of 0.028 kg is dropped from rest at a height of 1.0 meters above the ground. assuming the energy in the ball is conserved, how much kinetic energy will the ball have when it is 0.5 meters above the ground?

0.137 J

Explanation:

The conservation of energy states that the mechanical energy of the system is conserved:

where

is the potential energy, where m is the mass, g is the gravitational acceleration and h the height above the ground

is the kinetic energy, where m is the mass and v is the speed

- When the ball is dropped, the kinetic energy is zero (because it starts from rest). So, the mechanical energy is just potential energy:

- When it is h=0.5 m above the ground, part of the energy is now kinetic energy. The potential energy now is

And since the mechanical energy is conserved, we can write

So, the kinetic energy is 0.137 J.

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