Physics - W.E.P. Question with Solution | TestHub

PhysicsW.E.P.Conservative force & potential energyEasy2 minPYQ_2020

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The potential energy of a particle of mass $5 kg$ moving in the x - y plane is given by $U = (- 7 x + 24 y) J .$ $x$ and $y$ are in meter. If the particle starts from rest from origin then speed of the particle at $t = 2 s$ is

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Solution:

$F = - \frac{\partial U}{\partial x} \hat{i} - \frac{\partial U}{\partial y} \hat{j} = 7 \hat{i} - 24 \hat{j}$

$∴$ $a_{x} = \frac{F_{x}}{m} = \frac{7}{5} = 1.4 m s^{- 2}$

$a_{y} = \frac{F_{y}}{m} = - \frac{24}{5}$

$= 4 .8 m s^{- 2}$ along negative y-axis

$∴$ $v_{x} = a_{x} t = 1.4 \times 2$

$= 2 .8 m s^{- 1}$ along negative y-axis

And $v_{y} = 4.8 \times 2 = 9 .6 m s^{- 1}$

$∴$ $v = \sqrt{v_{x}^{2} + v_{y}^{2}} = 10 m s^{- 1}$

Stream:JEESubject:PhysicsTopic:W.E.P.Subtopic:Conservative force & potential energy

⏱ 2mℹ️ Source: PYQ_2020

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