Question

A body of mass 4kg is moving with a momentum of 12kg ms"!. Its kinetic energy is
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Answer 1

$\huge\underline{\underline{\red{\textbf{Solution : -}}}}$

• mass of body = 4kg
• momentum of body = 12 kg m/s

As we know that

$\boxed{\underline{\green{\textrm{Momentum = mv}}}}$

where,

• m = mass of body
• v = velocity of body

›› 12 = 4 × v

›› v = 12/4

›› v = 3m/s

$\boxed{\underline{\green{\bf{Kinetic\: Energy= \frac{1}{2}mv^{2}}}}}$

K.E = 1/2 × 4 × 3²

K. E = 2 × 9

K. E = 18J

Hence

• kinetic energy of body is 18 joules

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Answer 2

Answer:

18 joules

Explanation:

momentum =mass × velocity = 12kgm/ sec = 4kg×velocity = velocity = 12÷4 = 3 m/sec kinetic energy = 1/2×mass × velocity square = 1/2 × 4×3×3 = 18 joules