A particle is subjected two simple harmonic motions as : $\mathrm{x}_1=\sqrt{7} \sin (5t) \mathrm{~cm}$ and…
$\mathrm{x}_1=\sqrt{7} \sin (5t) \mathrm{~cm}$
and $x_2=2 \sqrt{7} \sin \left(5 t+\frac{\pi}{3}\right) \mathrm{cm}$
where x is displacement and $t$ is time in seconds. The maximum acceleration of the particle is $\mathrm{x} \times 10^{-2} \mathrm{~ms}^{-2}$. The value of x is :
- $175$
- $25 \sqrt{7}$
- $5 \sqrt{7}$
- $125$
Solution
From phasor,

$\therefore$ Amplitude of resultant $\mathrm{SHM}=7$
$\begin{aligned} & \phi=\tan ^{-1} \frac{2 \sqrt{7} \times \sqrt{3} / 2}{\sqrt{7}+2 \sqrt{7} \times \frac{1}{2}}=\tan ^{-1} \frac{\sqrt{21}}{2 \sqrt{7}}=\tan ^{-1} \frac{\sqrt{3}}{2} \\ & \therefore \quad \mathrm{X}_{\mathrm{R}}=7 \sin (5 \mathrm{t}+\phi) \\ & \quad \mathrm{a}_{\mathrm{R}}=-7 \times 25 \sin (5 \mathrm{t}+\phi) \\ & \therefore \mathrm{a}_{\max }=175 \mathrm{~cm} / \mathrm{sec}=175 \times 10^{-2} \mathrm{~m} / \mathrm{sec}\end{aligned}$
Asked in: JEE Main 2025 (02 Apr Shift 1)