1. Chapter 11 Class 7 Perimeter and Area
2. Concept wise
3. Circumference of circle

Transcript

Ex 11.3, 16 How many times a wheel of radius 28 cm must rotate to go 352 m? (ππππ π=22/7) Circumference of wheel In 1 rotation, wheel travels distance = Circumference Therefore, Number of rotations = (π·ππ π‘ππππ π‘πππ£πππππ)/(πΆππππ’ππππππππ ππ π€βπππ) Circumference of wheel Radius of wheel = r = 28 cm Circumference of wheel = 2πr = 2 Γ 22/7 Γ 28 = 2 Γ 22 Γ 4 = 44 Γ 4 = 176 cm = 176 Γ 1/100 m = 1.76 m ("1 cm = " 1/100 " m" ) Now Given, Distance travelled = 352 m Number of rotations = (π·ππ π‘ππππ π‘πππ£ππππ)/(πΆππππ’πππππππ ππ π€βπππ) β΄ Number of rotations = 352/1.76 = 352/176 Γ 100 = 176/88 Γ 100 = 88/44 Γ 100 = 2 Γ 100 = 200 β΄ Wheel rotates 200 times

Circumference of circle