Question

A girl is cycling and she covers 0.5 km in 2 minutes, next 0.75 km in 3 minutes and last 1 km in 4 minutes. Then her average speed is

• A. $4.16m{s}^{-1}$
• B. $0.25m{s}^{-1}$
• C. $0.25kmmi{n}^{-1}$
• D. $4.16kmmi{n}^{-1}$

Answer 1

Answer: (A), (C)

The correct options are
A

$4.16m{s}^{-1}$

C

$0.25kmmi{n}^{-1}$

In the first part of the journey, the distance covered = 0.5 and time = 2 minutes

In the second part of the journey, the distance covered = 0.75 and time = 3 minutes

And, In the third part of the journey, the distance covered =1 km and time = 4 minutes

So total distance covered= 2.25 and total time= 9 minutes

So,average speed = $\frac{\text{total distance}}{\text{total time}}$

= $\frac{2.25}{9}=0.25kmmi{n}^{-1}$

And,1 km = 1000 m and 1 minute = 60 s.

So average speed in $m{s}^{-1}$ = $\frac{0.25\times 1000}{60}=4.16m{s}^{-1}$