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Kinetic energy at the bottom position is equal to the potential energy at the starting position.
This potential energy is m*g*(1.50-0.80) = 0.5*10*0.7 = 3.5 kg*(m/s^2)*m = 3.5 joules.
Here 0.5 is the mass of 500 grams, expressed in kilograms;
g = 10 m/s^2 is the gravity acceleration;
1.50-0.80 = 0.7 is the difference of heights, expressed in meters.
Two energies, potential and kinetic, are equal due to mechanical energy conservation law.
Solved.
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