Q136 / 200 · JIPMER 2008 · Physics
The displacement of particle is given by
$x=a_0+\frac{a_1 t}{2}-\frac{a_2 t^2}{3}$
What is its acceleration?
- A$\frac{2 a_2}{3}$
- Correct answerB$-\frac{2 a_2}{3}$
- C$a_2$
- DZero
Solution
Key Idea : Acceleration is the rate of change of velocity and velocity is the rate of change of displacement.
The displacement equation is given by
$x=a_0+\frac{a_1 t}{2}-\frac{a_2 t^2}{3}$
Velocity $=$ rate of change of displacement
ie, $\quad v=\frac{d x}{d t}$
$\begin{aligned} & =\frac{d}{d t}\left(a_0+\frac{a_1 t}{2}-\frac{a_2 t^2}{3}\right) \\ & =0+\frac{a_1}{2}-\frac{2 a_2 t}{3} \\ & =\frac{a_1}{2}-\frac{2 a_2 t}{3}\end{aligned}$
Acceleration $=$ rate of change of velocity
$i e$,
$\begin{aligned} a & =\frac{d v}{d t} \\ & =\frac{d}{d t}\left(\frac{a_1}{2}-\frac{2 a_2}{3} t\right) \\ & =0-\frac{2 a_2}{3} \\ & =-\frac{2 a_2}{3}\end{aligned}$
Hence, the correct answer is option: 'B'.