An object starting from rest travels $20\mathit{ m}$ in the first $2\mathit{ s}$ and $160\mathit{ m}$ in next $4\mathit{ s}$. What will be the velocity after $7\mathit{ s}$ from the start?

An object starting from rest travels $20\mathit{ m}$ in the first $2\mathit{ s}$ and $160\mathit{ m}$ in next $4\mathit{ s}$. The velocity after $7\mathit{ s}$ of the object is $70\mathit{ m}/s$

Given initial velocity, $u=0\mathit{ m}/s$
At time, $t=2\mathit{ s},$ Displacement, $s=20\mathit{ m}$
Using equation, $s=\mathit{ut}+\frac{1}{2}a{t}^2$     $\Rightarrow \mathit{ }20=0\times t+\frac{1}{2}a\times 2^2$ 

Acceleration, $a=10\mathit{ m}/s^2$
so after $7\mathit{ s}$
 $v=u+\mathit{at }$ $\Rightarrow v=0+10\left(7\right)$ 

Final velocity, $v=70\mathit{ m}/s$