Question

A bicycle wheel, diameter 70 cm,is making 25 revolution in 10 sec.At what speed in km|/h is the bicycle traveling

Answer 1

d=2r
radius=35cm

2πr=
$2 \times 22 \div 7 \times 35$
= 220cm

Distance travelled =
$220 \times 25$
= 5500 cm

speed= 5500cm/10sec
= 5.50m/s

for converting to km/h =
$550 \div 100 \times 1000 \div 3600$
= 55÷36km/h

Answer 2

Answer:

Radius of a wheel = 70/2cm

= 35 cm

Circumference of a wheel = 2πr

= 2×22/7×35

= 220cm

1 revolution of a wheel. = 220cm

25 revolution of a wheel = 220×25

= 5500 cm

= 5500×1/100 m

=5500×1/100×1/1000km

= 55/1000

Number of revolution in 10 sec.= 55/1000

Number of revolution in 1 sec. = 55/10000

Distance moved in 1 hour =55/10000×60×60

= 55/100×36

= 1980/100

= 19.8km

hence the speed of bicycle travelling is 19.8km/hr.