help Please

[Ashiya]

The angular velocity of an object is the angle per unit of time through which an object rotates about a rotation centre. What is the angular velocity in radians per second of a bicycle tire of diameter 70 cm. when the bike is traveling at 30km/h?

 

[mdb]

30 km / 1 hr * 1 hr / 3600 sec * 100000 cm / 1 km * 1 rev / (70*PI) cm * (2*PI) rad / rev = 23.81 rad/sec

This is a unit conversion problem. Notice how all the units cancel out except rad/sec. The circumference on the bicycle tire (70*PI) is the distance the bicycle travels for every revolution of the tire.

 

[Deleted member 4993]

The angular velocity of an object is the angle per unit of time through which an object rotates about a rotation centre. What is the angular velocity in radians per second of a bicycle tire of diameter 70 cm. when the bike is traveling at 30km/h?

Do you know the equation:

(linear velocity of a point on a circle) v = (angular velocity of the point about the center of the circe) ? * (radius of the circle) r

or

v = ? * r

or are you supposed to derive it from fundamental definitions?