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JAMB Physics 2021 Paper

Question : 22

Total: 40

^{-1}

^{-2}

)

Solution:

Concept:

When air resistance is neglected, the total mechanical energy of the ball remains constant throughout its motion.

Explanation:

Given:

m = 0.1 \, \mathrm{kg}

u = 10 \, \mathrm{ms^{-1}}

h = 10 \, \mathrm{m}

, and

g = 10 \, \mathrm{ms^{-2}}

Total energy just before hitting the ground equals the sum of the initial kinetic energy and the initial potential energy at the top of the tower.

Initial kinetic energy:

\frac{1}{2}mu^2 = \frac{1}{2} \times 0.1 \times (10)^2 = 5 \, \mathrm{J}

Initial potential energy:

mgh = 0.1 \times 10 \times 10 = 10 \, \mathrm{J}

Therefore, total energy

= 5 \, \mathrm{J} + 10 \, \mathrm{J} = 15 \, \mathrm{J}

Answer:

15 \, \mathrm{J}

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