Question

Calculate the velocity of the ball if the angular speed is 7 rad/s and radius is .2 m.

(a) 2.5 m/s

(b) 1.4 m/s

(c) 4.5 m/s

(d) 1.0 m/s

The question was asked in semester exam.

Enquiry is from Regenerative Braking of DC Series Motors in section Braking of DC Motors & Induction Motors of Electric Drives

Answer 1

Right choice is (b) 1.4 m/s

Easy explanation: The velocity of the ball can be calculated using the relation V=Ω×r. The velocity is the vector product of angular speed and radius. V = Ω×r = 7×.2 = 1.4 m/s.