Question 14

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waecmaths question: 

Make u the subject of the formula, $E=\frac{m}{2g}({{v}^{2}}-{{u}^{2}})$

Option A: 

$\sqrt{{{v}^{2}}-\tfrac{2Eg}{m}}$

Option B: 

$\sqrt{\tfrac{{{v}^{2}}}{m}-\tfrac{2Eg}{4}}$

Option C: 

$u=\sqrt{v-\tfrac{2Eg}{m}}$

Option D: 

$u=\sqrt{\tfrac{2{{v}^{2}}Eg}{m}}$

waecmaths solution: 

$\begin{align}  & E=\frac{m}{2g}({{v}^{2}}-{{u}^{2}}) \\ & \frac{2gE}{m}={{v}^{2}}-{{u}^{2}}\text{       }\!\!\{\!\!\text{ Multiply both sides by }\tfrac{2g}{m}\} \\ & {{u}^{2}}={{v}^{2}}-\frac{2gE}{m} \\ & u=\sqrt{{{v}^{2}}-\frac{2gE}{m}} \\\end{align}$

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