Question

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

• A. $22\text{m/s}$
• B. $25\text{m/s}$
• C. $27\text{m/s}$
• D. $29\text{m/s}$

Answer 1

The correct option is C $27\text{m/s}$

Given, $x=3t^3+4$
We know that the average speed is given by $\frac{(x_f-x_i)}{t}$
So, at $t=0,x_i=0+4=4\text{m}$
and, at $t=3sec,x_f=3\times 3^3+4=85\text{m}$
Thus, average speed $=\frac{85-4}{3}=27\text{m/s}$