e d g e - education for disability and gender equity

PHYSICS
CONTENTS

1 Work
2 Energy
3 Momentum
4 Center of Gravity
   
5 ACTIVITY
6 RESOURCES
   

CENTER of GRAVITY

In our wheelchair activities, it is critical for the people in the wheelchairs to stay IN them. To accomplish this, there must be a steady center of the mass. Yet, there is great variety in the ways that people are built - particularly people with disabilities.

This is why wheelchairs have moveable center points for attaching the center of the wheel to the frame. Ideally, a wheelchair rider wants to have a center of mass that allows for the greatest use of arm energy while maintaining the lowest center of gravity. Also important is to have front wheels that create the least amount of resistance for the surfaces most often used. So a wheelchair for a basketball player might have very hard, smooth front wheels while the same rider might have larger, softer, more ‘forgiving’ front wheels for use on streets.

Additional Information:

HOW TO SELECT A WHEELCHAIR USING ANSI / RESNA STANDARDS

How tippy is a wheelchair? Let's face it, the world is not flat. Hills, ramps, curb cuts, and sidewalks with side slopes are just a few of the reasons you might want to know how tippy your wheelchair will be.

The lower the center of gravity, the farther over an object can lean. Thus, by concentrating the weight of buildings, cars and wheelchairs as low as possible, designers make them more stable.

Three examples of things that can cause you to tip are:

  1. going up a slope where your upper body (is off-center) backwards
  2. going down a slope where your upper body is off-center forwards
  3. on a level surface in motion when you run into a negative force (a bump or curb) against your front wheel but your upper body keeps going forward

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