Question

33.
Class 9
INDIAN TALENT OLYMPIAD
If the wheel of the car with 80 cm diameter makes 360 revolutions per minute. Find the
speed of the car in km/hr.

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Answer 1

Answer:

2πr = 40 cm (given)

360×40 / 60 × 60

Answer 2

GIVEN,

DIAMETER = 80 cm

SO, RADIUS = 40 cm

CIRCUMFERENCE OF THE WHEEL = 2πr

=

$= 2 \times \frac{22}{7} \times 40 \\ coverting \: it \: into \: kilometers \: \\ = 2 \times \frac{22}{7} \times \frac{40}{100000}$

1 HOUR = 60 MINUTES

SPEED OF THE CAR = CIRCUMFERENCE × REVOLUTIONS PER MINUTE

$= 2 \times \frac{22}{7} \times \frac{40}{100000} \times (360 \times 60) \\ = \: \frac{54.29 \: km}{hrs}$