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VITEEE 2016 Paper

Section: Physics

Question : 1 of 125

Marks: +1, -0

The potential energy of a system increases if work is done

Solution:

Potential energy

U

for a system is defined as:

W_{\;\text{int}\;} = -\Delta U = -(U_f - U_i) \ldots (1)

\int\limits_{i}^{f} \vec{F} \cdot \vec{dr} = -(U_f - U_i) \ldots (2)

\Rightarrow

Where

\vec{F}

is an internal conservative force, and

W_{\;\text{int}\;}

is work done by the internal conservative force.

\Rightarrow

U

increases then

U_f > U_i

, or the term

-(U_f - U_i)

will be

-v e

\Rightarrow W_{\;\text{int}\;}

will become

-v e

\therefore

System has done work against the conservative force

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