Light travels in straight lines. Once a light has been produced, it will keep moving in a straight line until it hits something else. Shadows are evidence of light traveling in straight lines. An object blocks light so that it can’t reach the surface where we see the shadow.
For an object`s motion, the Kinematic equation is,

Here, v is the final velocity and h is stands for the height of the object and a is the acceleration of the object.
As according to question,
and 
Thus, putting these values in above equation, we get

or


Therefore, initial velocity is 2.8 m/s
1,000 grams = 1 kilogram
so 55 megagrams = 55,000 kilograms
100 cm = 1 meter
so 500 cm = 5 meters
Acceleration of gravity on Earth = 9.8 m/s²
Weight = (mass) x (gravity)
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Work = increase in potential energy =
(weight) x (height) =
(mass) x (gravity) x (height) =
(55,000 kg) x (9.8 m/s²) x (5 m) =
2,695,000 joules .
If you compare the energy at two different times in an equation, you'll see no difference, because it's been conserved. The total energy of a system is the sum of its energy in motion - its kinetic energy - and its energy due to its position, which is its potential energy