Question 4 - Train Speed and Distance Calculations - Questions at the end of the chapter - Chapter 8 Class 7 - Measurement of Time and Motion (Curiosity)

Question. A train travels 180 km in 3 h. Find its speed in (i) km/h, (ii) m/s, (iii) What distance will it travel in 4 h if it maintains the same speed throughout the journey?

Answer.

(i) Speed in km/h

Use the formula: Speed = Distance ÷ Time

$$\begin{aligned} \text{Speed} &= \frac{\text{Distance}}{\text{Time}} \\[8pt] &= \frac{180 \text{ km}}{3 \text{ h}} \\[8pt] &= 60 \text{ km/h} \end{aligned}$$

(ii) Speed in m/s

To convert km/h to m/s, multiply by 5/18:

$$\begin{aligned} \text{Speed} &= 60 \text{ km/h} \times \frac{5}{18} \\[8pt] &= \frac{300}{18} \\[8pt] &\approx 16.67 \text{ m/s} \end{aligned}$$

(iii) Distance in 4 h

Use the formula: Distance = Speed × Time

$$\begin{aligned} \text{Distance} &= \text{Speed} \times \text{Time} \\[8pt] &= 60 \text{ km/h} \times 4 \text{ h} \\[8pt] &= 240 \text{ km} \end{aligned}$$

The train will travel 240 km in 4 hours.