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A 4-kg object falls vertically a distance of 5 m. its potential energy has changed by approximately how much?
a. it has increased by 200 j.
b. it has increased by 20 j.
c. it has decreased by 20 j.
d. it has decreased by 200 j.

Respuesta :

Given:
m = 4 kg, the mass of the object
h = 5 m, distance fallen

Neglect air resistance.

The PE (potential energy) is 
PE = mgh = (4 kg)*(9.8 m/s²)*(5 m) = 196 J

The PE is converted into KE (kinetic energy) after the fall. 
Therefore the PE decreased by 196 J ≈ 200 J

Answer: d. It has decreased by 200 J

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