Please solve question no.9.
Dear student,
Diameter of the wheel = 84 cm
Let the radius of the wheel be R cm
Radius of the wheel = 84/2 cm = 42 cm
No. of revolutions wheel makes = 5 rev/sec
Since, 1 revolution = 2πR
Speed of the wheel = 5 × 2πR rev/sec
= 5 × 2 × 22/7 × 42 = 1320 cm/sec
= 13.20 m/sec
= 13.20 × 3600/1000 km/h
= 47.52 km/h
Regards