An object of mass 100g projected vertically upwards from the ground level has a velocity of 20ms^-1 at a height of 10m. calculate its initial kinetic energy at the ground level.[g = 10ms^-2, neglect air resistance]

10 J

20 J

30 J

50 J

Correct answer is C

Using, v² = u² - 2gx

(20)² = u²1/2 x 10 x 10

u² = 600(m/s)²

initial K.E = - mu²

= \(\frac{1}{2}\) x 600

= 30 J

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An object of mass 100g projected vertically upwards from the ground level has a velocity of 20ms-1 at a height of 10m. calculate its initial kinetic energy at the ground level.[g = 10ms-2, neglect air resistance]