Answer:
720 J
Explanation:
The gravitational potential energy that Essam loses for every metre is given by:

where
m=72 kg is Essam's mass
is the gravitational field strength
is the difference in height
By substituting the numbers into the formula, we find

Answer:

Explanation:
<u>Free Fall Motion</u>
A free-falling object refers to an object that is falling under the sole influence of gravity. If the object is dropped from a certain height h, it moves downwards until it reaches ground level.
The speed vf of the object when a time t has passed is given by:

Where 
Similarly, the distance y the object has traveled is calculated as follows:

If we know the height h from which the object was dropped, we can solve the above equation for t:

The stadium is h=32 m high. A pair of glasses is dropped from the top and reaches the ground at a time:

The pen is dropped 2 seconds after the glasses. When the glasses hit the ground, the pen has been falling for:

Therefore, it has traveled down a distance:

Thus, the height of the pen is:

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Hope this helps! :)
Kinetic energy is calculated through the equation,
KE = 0.5mv²
At initial conditions,
m₁: KE = 0.5(0.28 kg)(0.75 m/s)² = 0.07875 J
m₂ : KE = 0.5(0.45 kg)(0 m/s)² = 0 J
Due to the momentum balance,
m₁v₁ + m₂v₂ = (m₁ + m₂)(V)
Substituting the known values,
(0.29 kg)(0.75 m/s) + (0.43 kg)(0 m/s) = (0.28 kg + 0.43 kg)(V)
V = 0.2977 m/s
The kinetic energy is,
KE = (0.5)(0.28 kg + 0.43 kg)(0.2977 m/s)²
KE = 0.03146 J
The difference between the kinetic energies is 0.0473 J.