Advertisements
Advertisements
Question
A cart wheel makes 9 revolutions per second. If the diameter of the wheel is 42cm, find its speed in km per hour. (Answer correct to the nearest km)
Advertisements
Solution
The Circumference of a Circle with diameter d is πd
The Circumference of a Circle with diameter 42cm is π x 42
= `(22)/(7) xx 42`
= 22 x 6
= 132cm
⇒ distance moved in 1 revolution = 132cm
Total distance moved in 9 revolutions
= 9 x 132cm
= 1188cm
Total distance moved in 1 second = 1188cm
⇒ Total distance moved in 1 hour
= 1188cm x 60 x 60
= 4276800cm
= `(4276800)/(100 xx 1000)"km"`
⇒ Speed = 42.7km/hr.
∴ Speed = 42.7km/hr.
APPEARS IN
RELATED QUESTIONS
Find the area of the sector of a circle whose radius is 14 cm and angle of sector is 45º
A horse is tied to a pole with 28m long string. Find the area where the horse can graze.
Four equal circles, each of radius 5 cm touch each other as shown in fig. Find the area included etween them.
Find the perimeter of the shaded region in the figure, if ABCD is a square of side 14 cm and APB and CPD are semicircles.
The sum of the radii of two circles is 7 cm, and the difference of their circumferences is 8 cm. Find the circumference of the circles.
In a circle of radius 21 cm, an arc subtends an angle of 60° at the centre. The length of the arc is
The radius of the circle is given below; find the area.
28 cm
Find the area grazed by a horse tied with a 11. 2 m rope to a corner of a field measuring 25m by 15 m.
Find the radius of a circle whose circumference is equal to the sum of the circumferences of two circles of radii 15 cm and 18 cm.
