A body having a mass 100 gram is allowed to fall freely from a height 100 g under the action of gravity. Its kinetic energy after 4 seconds be (take g - 10 m/ $s^{2}$ )

16 J

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160 J

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80 J

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800 J

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Solution

The correct option is C 80 J
Given,

Initial velocity, $u = 0$

Time, $t = 4 sec$

Apply equation of kinematic.

$V = u + g t$

$V = 0 + 10 \times 4 = 40 m s^{- 1}$

Kinetic energy, $K . E = \frac{1}{2} m V^{2} = \frac{1}{2} \times 0.1 \times 40^{2} = 80 J$

Hence, kinetic energy is $80 J$

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A body having a mass 100 gram is allowed to fall freely from a height 100 g under the action of gravity. Its kinetic energy after 4 seconds be (take g - 10 m/s2)

The correct option is C 80 JGiven, Initial velocity, u=0 Time, t=4sec Apply equation of kinematic. V=u+gt V=0+10×4=40ms−1 Kinetic energy,K.E=12mV2=12×0.1×402=80J Hence, kinetic energy is 80J

A body having a mass 100 gram is allowed to fall freely from a height 100 g under the action of gravity. Its kinetic energy after 4 seconds be (take g - 10 m/ $s^{2}$ )

The correct option is C 80 J
Given,

Initial velocity, $u = 0$

Time, $t = 4 sec$

Apply equation of kinematic.

$V = u + g t$

$V = 0 + 10 \times 4 = 40 m s^{- 1}$

Kinetic energy, $K . E = \frac{1}{2} m V^{2} = \frac{1}{2} \times 0.1 \times 40^{2} = 80 J$

Hence, kinetic energy is $80 J$