**Problem
4:** A motor car is travelling at a speed of 30 ms^{-1}. If
the wheel has a diameter of 1.5 m, find its angular speed in rad/s and rev/ s.

**Solution**

**Strategy:** The linear speed of the wheels of the car is to be converted to its angular speed. Remember, radius is half the diameter.

**Given** Linear speed = v = 30 ms^{-1} Radius of the wheel = (1.5/2) = 0.75 m

**Required ** Angular speed = ω (in radians and revolutions) = ?

Now the formula for converting linear speed to angular is

Put the values

Now to convert radians to revolutions, we have 2π radians = 1 revolution

So, in radians, the angular velocity = 6.36 rev/s.

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