A running man has the same kinetic energy as that of a boy of half his mass. The man speed up by $2{\rm{\;m}}{{\rm{s}}^{ - 1}}$ and the boy changes his speed by $x = {\rm{m}}{{\rm{s}}^{ - 1}}$, so that the kinetic energies of the boy and the man are again equal. Then x in ${\rm{m}}{{\rm{s}}^{ - 1}}$ is

JEE PHYSICS MCQ: WORK-ENERGY-POWER

1 Medium

1 of 1

Analyzing +4 | -1

A running man has the same kinetic energy as that of a boy of half his mass. The man speed up by

2\mathrm{\;m}{\mathrm{s}^{ - 1}}

and the boy changes his speed by

x = \mathrm{m}{\mathrm{s}^{ - 1}}

, so that the kinetic energies of the boy and the man are again equal. Then x in

\mathrm{m}{\mathrm{s}^{ - 1}}

View answer and explanation

Correct option: B

+ 2\sqrt 2

Option B (

+ 2\sqrt 2

) is correct because it is derived from equating the kinetic energies of the man and boy before and after the speed changes.

Practice All Chapter MCQs →

72 \mathrm{~km} / \mathrm{hr}

10 \mathrm{~m}

80 \%

1 \mathrm{~kg}

m

h

75 \%

m

v

M

m^{\prime}

v_1