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# If the unit of force and length each increased by 4 times , then the unit of energy is increased by

$(a)\;16 \;times \quad (b)\;8\;times\quad (c)\;2\;times \quad (d)\;4\; times$

Dimensionally, Force is represented as $[MLT^{-2}]$ and Length as $[L]$.
$\Rightarrow$ Energy $= F\;d$ is represented as $[MLT^{-2}] \times [L] = [ML^2T^{-2}]$.
Therefore, if Force and length are quadrupled in value, Energy $= 4[MLT^{-2}] \times 4[L] = 16[ML^2T^{-2}]$.
$\Rightarrow$ the unit of energy increased 16 times.
edited Aug 25, 2014