MUSSBERGER

Unless it's a grassy down slope.

bobt993

actually if your car is sliding on the track, leaves the track and hits wet grass it will pick up speed (yes it will). I have unfortunately had this happen avoiding a spinning car on a drying track and when I looked the data trace it sure did happen.

winders

Not possible unless you are sliding downhill.......

Scott

sundog

You will have less deceleration on the grass, and therefore it seems like the car is speeding up. The velocity vector of the center of mass will not increase without power being supplied to accelerate the car.

winders

As sundog suggests, even wet grass has friction so the car will continue to slow down, so the car cannot pickup speed unless their is enough slope for gravity to overcome the friction from the grass. Simple physics really....

Scott

Circuit Motorsports

Just remember that a spinning car is not simple physics. And I'd bet that bobt993 is talking about actual data when he mentions something that shows a speed increase.

winders

A spinning object is not different than a non-spinning object in this situation. At least in regards to the acceleration issues being discussed. The speed of the spin may very well increase but the speed of the car cannot.

Scott

Circuit Motorsports

It is different. Think about how the speed of the spin could increase and work backwards towards what if the speed of the spin decreased....

bobt993

I tried to arrest this by sending a PM. Linear velocity is handled different than angular velocity where you must factor in the physical radius. V is proportional to the R. Cars go off tracks in corners where they are using grip along a radius to move forward (hopefully). If you go straight off after locking up your brakes that is a different situation and not what I encountered. My car swerved avoiding a spinning car then continued into a very wet corner where the car lost grip from leaving the track prior. The once loss of asphalt lat grip to now grass (which is less than half that of asphalt when wet) changed the corner radius slide I attempting to stay on. " R" basically went to infinity and ended at a guard rail.

winders

Except that you are going from a surface with more friction to one with less friction. So the speed of the spin cannot decrease any faster than the speed of the car compared what was happening on pavement. The rate of spin could not decrease any faster in relation to the linear velocity so the linear speed cannot increase.

Scott

magnetic1

Bob, I agree with you on many things, but this one I dont. You cant introduce more forces than you had before.

It is impossible to accelerate by going off into wet grass unless you either hit the gas or go downhill. Data may have showed an increase in velocity which was a result of one of the other two scenarios.

Rate of deceleration will be less, sure. Acceleration? No. That would be defying laws of physics.

bobt993

Eric,

I think were arguing two sides of a coin. My point is leaving a track onto a wet surface and losing the forward motion leaving the corner the car does pick up speed in the direction you want least (towards the wall). The sensation is the car is accelerating just not in the direction you wanted (you have traded cornering speed for a very fast slide in one direction). You are losing one vector of your course direction and exchanging angular velocity for a somewhat larger radius towards a very hard surface.

J richard

...I miss Kibort...

J richard

...he would have charts & graphs...

winders

But, that is not what you said previously. You said:

"actually if your car is sliding on the track, leaves the track and hits wet grass it will pick up speed (yes it will)."

That statement is false. The direction can change, but the speed does not increase. In fact, it is always decreasing.

This link explains the feeling of acceleration:

http://courses.ncssm.edu/aphys/labs/elab1/jerk.html

Scott