Question

A boy has to cover 72 km in 4 hr. What should be his speed in m/s?

Answer 1

Answer:

he has to cover 18,000 m in 1 hour

Answer 2

Answer:

The speed of the boy is 5 m/s

Explanation:

Given :

A boy has to cover 72 km in 4 hr

To find :

the speed of the boy in m/s

Solution :

Distance covered = 72 km

Time taken = 4 hr

 $\boxed{\bf Speed=\dfrac{distance \ covered}{time \ taken}}$

 Speed = 72 km/4 hr

Speed = 18 kmph

Therefore, the speed of the boy is 18 kmph

We have to convert kmph to m/s

• 1 km = 1000 m
• 1 hr = 3600 sec

$\sf 1 \ kmph=\dfrac{1000 m}{3600 sec} \\\\ \longrightarrow \sf 1 \ kmph=\dfrac{10}{36} m/s \\\\ \longrightarrow \boxed{\sf 1 \ kmph=\dfrac{5}{18} m/s}$

⟶ 18 kmph = 18 × 5/18 m/s

⟶ 18 kmph = 5 m/s

So, the speed of the boy is 5 m/s