The cart travels the track again and now experiences a constant tangential acceleration from point A to point C. The speeds of the cart are 13.8ft/s at point A and 16.8ft/s at point C. The cart takes 5.00s to go from point A to point C, and the cart takes 1.90s to go from point B to point C. What is the cart's speed at point B? Express your answer numerically to three significant figures in feet per second.