Question

A particle returns to the starting point after $10\text{s}$. if the rate of change of velocity during the motion is constant, then its location after $7\text{s}$ will be same as that after

• A. $3\text{s}$
• B. $4\text{s}$
• C. $5\text{s}$
• D. $6\text{s}$

Answer 1

The correct option is A $3\text{s}$

As the particle returns to its starting position after $10\text{s}$, we can say
$0=u\left(10\right)-\frac{1}{2}a(10{)}^2$ (By second equation of motion)
$\Rightarrow \frac{u}{a}=5$
Distance at which the particle will change its direction of motion is given by
$0=u-at$
$\Rightarrow t=\frac{u}{a}$
$\therefore t=5\text{s}$

$\Rightarrow$ Location of the particle at $(t=7\text{s})$ = Location of the particle at $(t=3\text{s})$