B) The radius of a bicycle wheel is 50cm. In one-ninth of a second, it turns through 80° about its center, which is fixed. How many kilometers does a point on the rim of the
wheel travel in one hour?​

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Given data:

Radius r = 50cm

Time taken by the wheel to turn 80 degree = 1/9 seconds

= > In one second, wheel turns 720 degree

We know that one revolution is 360 degree

Therefore in one second, it takes 2 revolutions

In one hour i.e. 3600 seconds, it takes 7200 revolutions

Distance travelled by the wheel in one revolution is equal to the circumference of the wheel.

Distance travelled in one revolution = 2 π r = 2 π x 50 = 100 π cm

Distance travelled in one hour i.e. for 7200 revolution = 720000 π cm

So, distance travelled by the point on the rim of the wheel in an hour = 7.2 π km = 22.6 km

Step-by-step explanation:

if you explain the the question more correctly i might be able to answer this better

step-by-step explanation: