Changing speed (non-uniform circular motion)

Question

A cart is going around a circular track. The cart is located at a position. Which is defined by the angle theta, 28 degrees above horizontal.The radius of the track is 2.5 m. At this time the cart is speeding up at a rate of 2.1 m/s². What is the speed (v₄) of the cart at this time?

Answer 1

Since the cart took a second to increase a speed by 2.1; the new speed is Vo+2.1. Next second=Vo+4.2...................

V4=Vo+2.1*4=Vo+8.4m/s.