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प्रश्न
How much work is needed to be done on a ball of mass 50 g to give it a momentum of 5 kg cm s-1?
उत्तर
Kinetic energy is related to momentum as
K.E. where K = `p^2/(2 m)` and p is the momentum of the body
K.E. is nothing but work done
∴ K.E. = Work done = `("momentum")^2/(2 xx "mass of body")`
= `(5)^2/(2 xx (50/1000))`
= `(5 xx 5)/(2 xx (1/20))`
Work done = `25/(1/10)`
= 25 × 10
= 250 J
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