When you ride a bicycle in a straight line at one speed, your acceleration is zero.

What if you ride at one speed, but on a circular track?

Remember the definitions of SPEED and VELOCITY....

Speed gives only a magnitude ( 10 mi/hr, 400m/s, etc.)

Velocity gives a speed with a direction ( 10 mi/hr North, 400m/s at +30° )

So, when riding around in a circle, your direction constantly changes... this means that you are accelerating!

How can you prove this?

When you make a turn or ride in a circle, you must lean toward the center of the turn right?  This shows that somw force is pushing you toward the center of the trun. What does a force do to a mass?  It accelerates it! Now you know why you have to lean into a curve.  If you remain totally upright, you keep going straight, or you fall off your bike.


Even when your speedometer keeps reading one constant number, you are accelerating if you are changing direction!  The PROOF: Just by turning, you must lean in response to the force pushing you toward the center of the turn.