Question

A car accelerates uniformly from $20{\text{ms}}^{–1}$ to $50{\text{ms}}^{–1}$ while entering the motorway, covering a distance of $200\text{m}$. Then the acceleration of the car will be:

• A. $4.25{\text{ms}}^{-2}$
• B. $6.30{\text{ms}}^{-2}$
• C. $5.25{\text{ms}}^{-2}$
• D. $5.65{\text{ms}}^{-2}$

Answer 1

The correct option is C $5.25{\text{ms}}^{-2}$

Given,
$s=200\text{m}$
$u=20{\text{ms}}^{-1}$
$v=50{\text{ms}}^{-1}$
$a=?$
Using $3^{rd}$ equation of motion i.e.
$v^2=u^2+2as$
$(50{)}^2=(20{)}^2+(2\times a\times 200)$
$2500=400+400a$
$400a=2500-400=2100$
$\therefore a=\frac{2100}{400}=5.25{\text{ms}}^{-2}$