Question

The displacement of the particle is given by $x=3t^2+2t$ in $\text{m}$. The average speed of the particle in $4\text{sec}$ is

• A. $12\text{m/s}$
• B. $14\text{m/s}$
• C. $15\text{m/s}$
• D. $20\text{m/s}$

Answer 1

The correct option is B $14\text{m/s}$

Given, $x=3t^2+2t$
We know that the average speed is given by $\frac{(x_f-x_i)}{t}$
So, at $t=0,x_i=0+0=0\text{m}$
and, at $t=4sec,x_f=3\times 4^2+2\times 4=56\text{m}$
Thus, average speed $=\frac{56}{4}=14\text{m/s}$