# Skidding problem

1. Nov 8, 2006

### andrewtsoi34

Skidding problem [Urgent]

Why the limiting speed of the venhicle without skidding is independent of its mass?

For example, why lorries may have to go at a slower speed than the 25m/s
limit for cars

But why this does't depend on the mass but the speed

2. Nov 8, 2006

### Danger

It's dependent upon a lot of things, not the least of which is mass. Other factors include weight distribution, tire compounds and quality, road surface conditions, etc.. I'll leave the details for others more versed in the matter.

3. Nov 10, 2006

### vijay123

andrew...if you have studied rotaional motion and the parallel axis theorem then here is how it goes.....snece the vehicle is rolling...the total kinectic energy possesed by it is .5mv^2+.5Iw^2....were i is the rotational inertia and w is rotational spped...since the i for wheels is .25mr^2..think u so....then..we can eqaute this to the firctional energy...which is equivalent to the friction force times the distance travelled...u know that frictional force is dependent on the mass of vehicle....hce....if we would equate these variable....mass would get cancelled of!...

4. Nov 10, 2006

### DaveC426913

I love these "urgent" vehicular motion questions.

I imagine andrew furiously typing away on his laptop in the car. "Urgent! What is the braking distance on a 97 Chevy?"
Followed 20 seconds later by "Never mind..."

5. Nov 11, 2006

### QuantumCrash

A lorry has a lower speed limit simply because it takes longer to stop normally. ( it probably stops just as quickly as any other vehicle if it hits a wall though... almost)