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

PhysicsW.E.P.MiscellaneousEasy2 minPYQ_2015

PhysicsEasysingle choice

A block of mass $10 kg$ , moving in $x$ direction with a constant speed of $10 m s^{- 1}$ , is subjected to a retarding force $F = [(0 .1) x] J m^{- 1}$ during its travel from $x = 20 m$ to $30 m$ . Its final kinetic energy will be:NEET 2015 (Phase 1)

Options:

Answer:

Solution:

$m = 10 k g, u = 10 m s^{- 1}$

Final KE will be given by

$K E_{f} = K E_{i} + W$

$= \frac{1}{2} m u^{2} + \int_{20}^{30} (- 0 .1 x) d x$

$= \frac{1}{2} \times 10 \times 100 + (- 0.1) {[\frac{x^{2}}{2}]}_{20}^{30}$

$= 500 + \frac{(- 0.1)}{2} (900 - 400)$

$K E_{f} = 500 + \frac{(- 0.1) 500}{2}$ $= 475 J$

Stream:NEETSubject:PhysicsTopic:W.E.P.Subtopic:Miscellaneous

⏱ 2mℹ️ Source: PYQ_2015

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