Question

A particle starts from rest. Its acceleration at time $t=0$ is $5{\text{ms}}^{-2}$ which varies with time as shown in figure. The maximum speed of the particle will be

• A. $7.5{\text{ms}}^{-1}$
• B. $15{\text{ms}}^{-1}$
• C. $30{\text{ms}}^{-1}$
• D. $7.5{\text{ms}}^{-1}$

Answer 1

The correct option is B $15{\text{ms}}^{-1}$

Area under $a-t$ graph corresponds to change in velocity
Hence $A=\frac{1}{2}\times 5\times 6=\Delta v=v-u$
As particle starts from rest $u=0,$
Hence $v=15\text{m/s}$
Hence the correct choice is (b).