Question

The position of a particle moving along x-axis is given by $x=(5t^2-4t+20)\text{m}$, where $t$ is in second. Find the magnitude average velocity between $1\text{s}$ and $3\text{s}$.

• A. $10\text{m/.s}$
• B. $16\text{m/.s}$
• C. $14\text{m/.s}$
• D. $5\text{m/.s}$

Answer 1

The correct option is B $16\text{m/.s}$

Given, $x=(5t^2-4t+20)m$
$t=1\text{s};x_{in}=5\times (1{)}^2-4\times (1)+20=21\text{m}$
$t=3\text{s};x_{in}=5\times (3{)}^2-4\times (3)+20=53\text{m}$
$v_{avrg}=\frac{\Delta x}{\Delta t}$
$v_{avrg}=\frac{(53-21)}{(3-1)}=16\text{m/s}$