MCQ
Velocity of a particle moving in a curvilinear path in a horizontal $X$ $Y$ plane varies with time as $\vec v = (2t\hat i + t^2 \hat j) \ \  m/s.$ Here, $t$ is in second. At $t = 1\  s$
  • A
    acceleration of particle is $8\  m/s^2$
  • B
    tangential acceleration of particle is $\frac{4}{{\sqrt 5 }} \ m/s^2$
  • C
    radial acceleration of particle is $\frac{6}{{\sqrt 5 }} \ m/s^2$
  • radius of curvature to the path is $\frac{5\sqrt 5}{{2 }} \ m$

Answer

Correct option: D.
radius of curvature to the path is $\frac{5\sqrt 5}{{2 }} \ m$
d
$\overrightarrow{\mathrm{V}}=2 \mathrm{t} \hat{\mathrm{i}}+\mathrm{t}^{2} \hat{\mathrm{j}}$

$\vec{a}=2 \hat{i}+2 t \hat{j}$

$|\vec{V}|=V=\sqrt{4 t^{2}+t^{4}}$

$a_{t}=\left(\frac{d V}{d t}\right)=\frac{1}{2 \sqrt{4 t^{2}+t^{4}}} \times\left(8 t+4 t^{3}\right)$

at $t=1 \quad a_{t}=\left(\frac{6}{\sqrt{5}}\right) \mathrm{m} / \mathrm{s}^{2}$

$a=\sqrt{2^{2}+(2 t)^{2}}=\sqrt{8} \mathrm{m} / \mathrm{s}^{2}$

$r=\sqrt{5}$

$a_{c}=\sqrt{a^{2}-a_{t}^{2}}=\sqrt{8-\frac{36}{5}}=\left(\frac{2}{\sqrt{5}}\right)$

$R=\left(\frac{V^{2}}{a_{c}}\right)=\frac{5}{\left(\frac{2}{\sqrt{5}}\right)}=\frac{5 \sqrt{5}}{2}$

$R=\left(\frac{5 \sqrt{5}}{2}\right) m$

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