The velocity of a particle is given by $v=2 t^2-8 t+15 \mathrm{~ms}^{-1}$. Find its instantaneous…

The velocity of a particle is given by $v=2 t^2-8 t+15 \mathrm{~ms}^{-1}$. Find its instantaneous acceleration at $t=5 \mathrm{~s}$.
  1. $18 \mathrm{~ms}^{-2}$
  2. $20 \mathrm{~ms}^{-2}$
  3. $5 \mathrm{~ms}^{-2}$
  4. $12 \mathrm{~ms}^{-2}$

Solution

Given, velocity, $v=2 t^2-8 t+15$ $ \text { time, } t=5 \mathrm{~s} $ Let acceleration be $a$. $ \begin{aligned} \because \quad & a=\frac{d v}{d t} \\ \therefore \quad & a=4 t-\left.8\right|_{t=5} \\ & =4 \times 5-8 \\ & =20-8 \\ & =12 \mathrm{~ms}^{-2} \end{aligned} $

Asked in: AP EAMCET 2021 (23 Aug Shift 1)

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