question_answer 32)

How many times a wheel of radius 28 cm must rotate to go 352 m? \[\left( \text{Take  }\!\!\pi\!\!\text{  = }\frac{\text{22}}{\text{7}} \right)\]

Answer:

                Radius of the wheel (r) \[=\text{28 cm}\] \[\therefore \] Circumference of the wheel \[\text{= 2 }\!\!\pi\!\!\text{ r cm}\] \[\text{= 2  }\!\!\times\!\!\text{  }\frac{\text{22}}{\text{7}}\text{  }\!\!\times\!\!\text{  28 cm}\] \[\text{= 176 cm}\] \[\therefore \] Number of times the wheel must rotate to go \[\text{352 m (or 352  }\!\!\times\!\!\text{  100 cm) =}\frac{352\times 100}{176}=200\]