Question

31. Find the momentum of a body of mass 100 g having a kinetic energy of 20 j​

Answer 1

Answer:

K.E=1/2(mv2)

m=100g= 1kg

k.E=20 J

so, 20=1/2 x0.1xv2

40=0.1xv2

400=v2

V=20m/s

Momentum ,p=mv

So, p=0.1kg x20 m/s

=2kgm/s

Answer 2

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Momentum of body = 2kgm/s

${\huge{\boxed{\mathcal{\red{Explanation}}}}}$

Important key words :

• Momentum is product of mass and velocity
• Kinetic energy is half of product of mass and square of velocity.

It is given that :

Mass of body = 100g = 0.1kg

Kinetic energy of body = 20J

Momentum of body = p = ?

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Now kinetic energy of a body is represented by

$\frac{1 }{2} \times m {v}^{2}$

After inputting the values in this equation for our

condition we get:

$20j = \frac{1}{2} \times 0.1 \times {v}^{2}$

$40 = 0.1 {v}^{2}$

$\frac{40}{0.1} = {v}^{2}$

$400 = {v}^{2}$

$v = \sqrt{400}$

$v = 20m \div s$

Thus we get velocity of body is 20m/s

Now since momentum = m × v

Thus we get momentum of this body =

$p = 20 \times 0.1$

$p = 2$

Thus momentum of body is 2kgm/s.

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BY SCIVIBHANSHU

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