Question

A car’s odometer reads $22687\text{km}$ at the start of a trip and $22791\text{km}$ at the end of the trip. If the trip takes $4$ hours, then the average speed of the car in
(i)${\text{km h}}^{-1}$ (ii) ${\text{m s}}^{-1}$ is

• A. (i) 20 (ii) 5.55
• B. (i) 36 (ii) 10
• C. (i) 18 (ii) 5
• D. (i) 26 (ii) 7.2

Answer 1

The correct option is D (i) 26 (ii) 7.2

We know that,
$\text{Average speed}=\frac{\text{Total Distance travelled}}{\text{Total time taken}}$
$\text{Average speed}=\frac{22791-22687}{4}{\text{km h}}^{-1}=\frac{104}{4}{\text{km h}}^{-1}=26{\text{km h}}^{-1}$
$=26\times \frac{5}{18}{\text{m s}}^{-1}=7.22{\text{m s}}^{-1}$