Rear Wheel Driven Car Rolling Friction

[pcdagr8]

if a rear wheel driven car is accelerated
i think...
1. on rear wheels friction is forward
2 on front wheels it is backward


my questions-
1.wats d direction of rolling friction on the car as a whole?(is dis question correct?)

2.which wheel will have greater magnitude of friction??

 

[denverdoc]

friction is always in direction opposite that of motion.

 

[pcdagr8]

friction is always in direction opposite that of motion.

going by your logic
You mean in pure rolling motion the friction should act backward??

 

[Doc Al]

friction opposes slipping between surfaces

A better way to describe friction is to say that it always opposes slipping between surfaces. Consider the rear tires. Without friction, they would just spin, slipping to the rear with respect to the road. Friction with the road opposes that slipping by acting towards the front. The friction accelerates the car forward, so friction and the car's motion are in the same direction.

 

[denverdoc]

Thanks Al, a nice explanation. I was only considering situation where there was already angular velocity and see now problem asks during acceleration. My bad.

 

[pcdagr8]

Thanks Al !
but u haven't answered my second question...
please see if u can tell me something about it.