Question

Calculate kinetic energy of a body of a mass 4 kg moving with a velocity of 0.2 m/s . If the velocity is doubled what will be the new kinetic energy.

Answer 1

1/2*mv^2=KE and double of velocity is 0.2*2=0.4 so,
1/2*4*0.4^2=1/2*4*0.16=2*0.16=0.32kJ

Answer 2

We know,

kinetic energy =

$\frac{1}{2} m {v}^{2}$
Given,m = 4 kg and v = 0.2 m/s.

thus, K.E. =

$\frac{1}{2} \times 4 \times 0.2 \times 0.2 \\ = > 0.08joule$
Now, when, velocity is doubled,new velocity = 0.4 m/s.

Thus, new K.E. =
$\frac{1}{2} \times 4 \times 0.4 \times 0.4 \\ = > 2 \times 0.16 \\ = > 0.32 \: joule$


Regards

KSHITIJ