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प्रश्न
A body of mass 10 kg is moving with a velocity 20 m s-1. If the mass of the body is doubled and its velocity is halved, find:
- the initial kinetic energy, and
- the final kinetic energy.
उत्तर
Let initial Mass, m1= 10 kg and velocity, v1 = 20 m/s
Final mass, m2 = 2 × 10 = 20 kg and velocity, v2 = 20/2 = 10 m/s
Initial kinetic energy, K1= `1/2 × mv^2`
= `1/2 ×10 ×(20)^2`
= `1/2 × 10 × 20 × 20`
= 2000 J
Final kinetic energy, K2 = `1/2 × mv^2`
= `1/2 × 20 ×(10)^2`
= `1/2 × 20 ×10 ×10`
= 1000 J
`"K"_1/"K"_2=2000/1000=1/2=2:1`
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