Question

4. A bicycle wheel, diameter 56 cm, is making
45 revolutions in every 10 seconds. Calculate
the speed, in kilometre per hour, of the
bicycle.​

Answer 1

Answer:

ANSWER

Since the diameter of the wheel is 56cm, its radius is 28cm.

In one revolution, the wheel covers the distance of one circumference.

Circumference of the wheel =2πr=2×

7

22

×28=176cm

Since the wheel makes 45 revolutions in 10 seconds, it makes

10

45

revolutions in one second.

Total distance covered in one second = No. of revolutions in one second

× circumference =

10

45

×176=792 cm/s

cm/s can be converted to km/hr using the formula cm/s ×

500

18

= km\hr

Now 792×

500

18

=28.512 km/hr

Answer 2

Answer:

28.512 km/hr

Step-by-step explanation:

C = 2π r = 2 × 22/7 × 28 = 176 cm

Distance travelled in 45 revolutions

176 × 45 = 7920 cm = 7920 / 100×1000 km

Time = 10 sec = 10 / 60 × 60 = hr

Speed = 7920/100×1000 ÷ 10/60×60 m

7920 / 100 × 1000 × 60 × 60 / 10 = 28512/1000

= 28.512 km/hr