A body of mass 2 ~kg is thrown up vertically with kinetic energy of 490 ~J . The height at which the kinetic energy of the body becomes half of its original value is

Correct answer: (B) 12.25 ~m. Potential energy at the required height =490/2=245 ~J Again, 245=2 × 10 × h or h=245/20 ~m=12.25 ~m

Q137 / 180 · AIIMS 2014 · Physics

A body of mass $2 \mathrm{~kg}$ is thrown up vertically with kinetic energy of $490 \mathrm{~J}$. The height at which the kinetic energy of the body becomes half of its original value is

A
$50 \mathrm{~m}$
Correct answer
B
$12.25 \mathrm{~m}$
C
$25 \mathrm{~m}$
D
$10 \mathrm{~m}$

Solution

Potential energy at the required height $=\frac{490}{2}=245 \mathrm{~J}$ Again, $245=2 \times 10 \times h$ or $h=\frac{245}{20} \mathrm{~m}=12.25 \mathrm{~m}$

Hence, the correct answer is option: 'B'.

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