RRB Group D 23-Oct-2018 Shift 3 Solved Paper

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Question : 85 of 100

Marks: +1, -0

A boy, of mass

50 \ { kg}

, runs up a staircase of 45 steps in

10 \ { s}

. If the height of each step is

14 \ { cm}

, find his power. Take

\ {g}=10 \ { ms}^{-2}

$310.55 \ { J}$
$315 \ { W}$
$337.5 \ { W}$
$315 \ { ms}$

Solution:

Given, mass of body,

{m}=50 \ {kg}

\ {h}=45 \ ×0.14=6.3 \ { m}

\ {t}=10 \ { s}

\ {g}=10 \ { m} \/ \ {s}^{2}

\ {PE}=\ {mgh}=50 \×10 \×6.3

=3150 \ { J}

Power of the body

=\ {PE} /

time

=

Energy

/

time

=3150 / 10=315 \ { W}

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