Question

A scooterist covers a distance of 3 kilometres in 5 minutes. Calculate his speed in
(a) centimetres per second (cm/s)
(b) metres per second (m/s)
â(c) kilometres per hour (km/h)

Answer 1

Speed of scooter :- a) 1000 ($\frac{cm}{s}$) b) 10($\frac{m}{s}$) c) 36($\frac{km}{h}$).

Explanation:

1. Distance(d) cover by scooter

  d = 3 km = 3000 m = 300000 cm

2. Time(t) taken by scooter to cover distance 3 kilometre

   t = 5 minute = 5 × 60 second = 300 second = $\frac{5}{60}$ hours = $\frac{1}{12}$ hours

3. From speed formula

  $Speed = \frac{distance}{time}$

a) Speed = $\frac{300000 cm}{300 s}$ = 1000 ($\frac{cm}{s}$)

b) Speed = $\frac{3000 m}{300 s}$ = 10 ($\frac{m}{s}$)

c) Speed = $\frac{3 km}{(\frac{1}{12}) h}$ = 36 ($\frac{km}{h}$)

Answer 2

Speed is the ratio of distance travelled and time is taken.

Explanation:

We know,

Speed = $\frac {distance}{time}$

1) 3 km = 300000 cm

 5 min = 300 sec

Speed = \frac {300000}{300}

 = $1000\ cmsec^-^1$

2) 3 km = 3000 m

5 min = 300 sec

speed = $\frac {3000}{300}$

 = $10\ msec^-^1$

3) Distance, = 3 km

5 min = 0.083 hr

speed = $\frac {3}{0.083}$

 = $36.01\ kmh^-^1$