Question

A travels at the speed of $30{\text{m s}}^{-1}$ for $4\text{s}$. If the objective of A was to cover $200\text{m}$ in $8\text{s}$, what speed must it travel with in the remaining time to cover the distance?

• A. $30{\text{m s}}^{-1}$
• B. $25{\text{m s}}^{-1}$
• C. $20{\text{m s}}^{-1}$
• D. $10{\text{m s}}^{-1}$

Answer 1

The correct option is C $20{\text{m s}}^{-1}$

Given:
Speed for the first $4\text{s}$ = $30{\text{m s}}^{-1}$

Distance travelled in first $4\text{s}$ = $30\times 4=120\text{m}$

Total distance to be covered = $200\text{m}$

$\therefore$ Remaining distance:$=200-120=80\text{m}$

Total time to be taken $=8\text{s}$

$\therefore$ Remaining time $=8-4=4\text{s}$

Thus, required speed =$\frac{\text{Distance}}{\text{Time taken}}=\frac{80}{4}=20{\text{m s}}^{-1}$