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Question
A cannon ball of mass 500 g is fired with a speed of 15 m s-1. Find:
- its kinetic energy.
- its momentum.
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Solution
(i) Mass of canon ball = 500g = 0.5 kg
Speed, v = 15m/s
Kinetic energy of ball = `1/2 xx "mass" xx ("velocity")^2`
`= 1/2 ×0.5 ×(15)^2`
`= 1/2 ×0.5 ×225`
`=56.25 "J"`
(ii) Momentum of ball p = mv = `1/2 xx 15`
= 7.5 kg ms-1
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