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Standard VIII

Chemistry

Potential Energy

A boy lifts a...

Question

A boy lifts a luggage from height 2m to 4m. The potential energy will become___the initial.

half

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double

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one-third

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one- fourth

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Solution

The correct option is B
double

Let initial height be $h_{1} = 2 m$

and final height be $h_{2} = 4 m$

Let mass of the luggage be $m$

Now, Inital potential energy, $P . E_{1} = m g h_{1} = 2 m g$

and final potential energy, $P . E_{2} = m g h_{2} = 4 m g$

$\frac{P . E_{2}}{P . E_{1}} = \frac{4 m g}{2 m g} = 2$

$P . E_{2} = 2 \times P . E_{1}$

$∴$ Potential energy becomes two times the initial.

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A boy lifts a luggage from height 2m to 4m. The potential energy will become___the initial.

The correct option is B double Let initial height be h1=2 m and final height be h2=4 m Let mass of the luggage be m Now, Inital potential energy,P.E1=mgh1=2mg and final potential energy,P.E2=mgh2=4mg P.E2P.E1=4mg2mg=2 P.E2=2×P.E1 ∴ Potential energy becomes two times the initial.