Question

A particle is moving in a straight line according to the formula $s=t^2+8t+12$. If s be measured in meter and $t$ be measured in seconds, then the average velocity of the particle in third second is

• A. $14meter/second$
• B. $13meter/second$
• C. $15meter/second$
• D. None of these

Answer 1

The correct option is B

$13meter/second$

Explanation for the correct option:

Find the average velocity of the particle in the third second is :

Given, a particle is moving in a straight line according to the formula $s=t^2+8t+12$.

Distance travelled in $3$sec $=3^2+8\times 3+12=9+24+12=45$

Distance travelled in $2$sec $=2^2+8\times 2+12=4+16+12=32$

Average velocity in the third second $=$ Distance travelled in the third second

$=$Distance travelled in $3$sec $-$Distance travelled in $2$sec

$$\begin{gathered} =45-32 \\ =13meter/second \end{gathered}$$

Hence, the correct option is (B).