Question

When a wheel 1m in diameter makes 30 rev/min the linear speed of a point on its rim in m/s is? a)pi b) pi/2 c) 30pi d)60pi

Answer 1

I got `b)`

Explanation:

Ok,
`30` rev/min correspond to `30/60=0.5` rev/sec or haf revolution at each second;
this corresponds to half a circle of `1m` of diameter each second.
We can say that `1m` diameter corresponds to a radius `r=1/2=0.5m`.
Half a circle corresponds to an arc length of half circumference or:
`1/2C=1/cancel(2)*cancel(2)pir=pi/2`m/s