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QJEEM23Ph611b: JEE Main 2023 Physics - Class 11 JEEM23Ph611b Solution: A body of mass is initially at rest. It starts moving…

A body of mass 2 kg2 \mathrm{~kg} is initially at rest. It starts moving unidirectionally under the influence of a source of constant power P. Its displacement in 4 s4 \mathrm{~s} is 13α2Pm\frac{1}{3} \alpha^{2} \sqrt{P} m . The value of α\alpha will be ______.

Step-by-Step Verified Solution

P=FvP = Fv

mvdvdt=Pm{{vdv} \over {dt}} = P

m∫0vvdv=∫0tPdtm\int_0^v {vdv = \int_0^t {Pdt} }

mv22=Pt{{m{v^2}} \over 2} = Pt

v=2Pmt1/2v = \sqrt {{{2P} \over m}} {t^{1/2}}

∫0sdx=2Pm∫0tt1/2dt\int_0^s {dx = \sqrt {{{2P} \over m}} \int_0^t {{t^{1/2}}dt} }

s=232Pmt3/2s = {2 \over 3}\sqrt {{{2P} \over m}} {t^{3/2}}

or s=232P2×43/2s = {2 \over 3}\sqrt {{{2P} \over 2}} \times {4^{3/2}}

=163P m= {{16} \over 3}\sqrt P ~m

So, α=4\alpha = 4

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