Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site mmintl.UUCP Path: utzoo!linus!philabs!pwa-b!mmintl!franka From: franka@mmintl.UUCP (Frank Adams) Newsgroups: net.physics Subject: Re: Friction Message-ID: <729@mmintl.UUCP> Date: Thu, 24-Oct-85 13:41:38 EST Article-I.D.: mmintl.729 Posted: Thu Oct 24 13:41:38 1985 Date-Received: Thu, 31-Oct-85 04:04:08 EST References: <956@decwrl.UUCP> Reply-To: franka@mmintl.UUCP (Frank Adams) Organization: Multimate International, E. Hartford, CT Lines: 20 Summary: [Not food] In article <956@decwrl.UUCP> shuster@oblio.DEC (ROBERT L. SHUSTER) writes: >It is very much easier to turn the wheel (using the steering wheel) of >a moving car than that of a stationary car. The surface area of tire >on the road does not change as it begins to rotate. The difference in >ease of turning, then, is the difference between friction on >stationary object and friction on a moving object. No, something quite different is happening in the moving car. The key is that the tires are not rigid. When you turn the wheel a little, you create stress in the tire near the road. If the car is not moving, turning the wheel further requires the tire to slip against the road, whence friction comes into play. For a moving car, that portion of the tire spins on out of contact with the road, relieving the stress. Thus friction plays little part in the ease of turning the wheel in a moving car (unless it becomes very low, such as on ice). Frank Adams ihpn4!philabs!pwa-b!mmintl!franka Multimate International 52 Oakland Ave North E. Hartford, CT 06108