Consider a bicyclist that is traveling at a constant speed of 5m/s.  During the observed time interval they ride along a straight road, then make a right turn, continuing in their new direction at 5m/s.  Do they ever accelerate?
 
 
 
 
 
 
 
 
 
 

A car is moving at a constant speed travels past a valley in the road, as shown.  Which of the arrows shown most closely approximates the direction of the carís acceleration at the instant that is at the position shown?
 
 

What if the car is speeding up?  Which way does the acceleration vector point then?