# What happens if you're sitting in a wheelchair and you turn only one wheel?

My friend was sitting in a wheelchair, with a cup of coffee in one hand. That made me wonder, how would the wheelchair move if he turned only one rear wheel?

He tried it, using his right hand to turn the right rear wheel. The wheelchair starting moving in a circle. No surprise. But I was interested in the radius of the circle.

The circular track of the right rear wheel on the ground, had a radius that was slightly larger than the distance between the rear wheels (i.e. the distance between the two points of contact between the rear wheels and the ground).

What determines the radius of the circular track of the left rear wheel (the unturned rear wheel)?

Possibilities that come to my mind are:

• Location of all four wheels
• The size and shape of the contact patch between the wheels and the ground
• The coefficient of friction between the wheels and the ground, and the weight of the system
• The diameter of the wheels
• Angular speed of the right rear wheel
• How the person is sitting within the chair (centred, or leaning to the left, leaning to the right)

(Assume the wheels are in parallel planes.)

• I can easily imagine interesting answers that are pure physics. Voted to reopen. Commented Nov 25, 2023 at 10:27
• "The wheelchair starting moving in a circle. No surprise." Why did you expect that? I put a food can on the table and gave it little impulses starting at the top rim of the right side and it moved in a straight line. Commented Jan 19 at 19:01