ok following on from the 'would an aircraft take off if it was on a conveyor belt?' thread, i still cant get my head around how a car travelling along a road at 50mph could drive into a lorry (via its ramp) without shooting forward and through the front!

fans of Knight Rider will know what i mean. those two chaps from mythbusters tried it themselves and proved that it does actually work and isnt a fake.

 

http://uk.youtube.com/watch?v=dYlstdCWzCY&feature=related

 

although interesting to watch, i dont think the guys explained it well enough for me to understand. the only thing i can think of is that once the rapidly-spinning tyre rolls onto the relationally stationary ramp, the wheels would lose all traction and skid - giving the driver enough time to hit the brakes. but in the clip above, we see the wheels just come to a stop all by themselves! and its not the driver braking cos the front wheels stop by themselves while the rear wheels are still doing 50mph.

 

im confused and feel a little foolish :o

because its the weight of the car, the wheel has no choice but to stop spinning, as there is not enough energy in the wheels to propel the car faster than it was already going. hard to explain.

 

you would think the tyres would screech a little though

I'd like to see them back off the truck at 55mph :)

Lets say an aircraft is flying at 550 MPH and a fly in the front of the cabin decides to fly to the rear of the plane.How fast would the fly have to be going to achieve this ?

Lets say an aircraft is flying at 550 MPH and a fly in the front of the cabin decides to fly to the rear of the plane.How fast would the fly have to be going to achieve this ?

 

relative to the plane or the ground or space?

ok to answer your first question lets look at teh front wheels first.

 

they are free wheeling.

 

Imagine they are on a skateboard, do they rotate if the car is driven forward or does the skateboard?

 

As for teh rear wheels as they engage the stationary ramp tehy suddenly impart a massive amount of load through the system. The weight of the car and the load cause teh torqu converter or clutch to slip for an instance which with teh friction of the tyres and the weight of the car stop teh car from skidding. this givess the driver a valuable abount of time to come off the throttle and control the car.

 

got it?

relative to the plane or the ground or space?

 

Ground.As the air speed is set to that.

Lets say an aircraft is flying at 550 MPH and a fly in the front of the cabin decides to fly to the rear of the plane.How fast would the fly have to be going to achieve this ?

Do you have to run at 551mph to get to the to the front of the plane ? Of course not . Your traction to the floor is what propels you . Similarly , the fly is using its wings in the relatively still air , otherwise it wouldn`t have to do anything : it would be propelled at 550mph backwards . What`s going on outside is irrelevant , I would have thought .

Just my 2P worth :p

I'd like to see them back off the truck at 55mph :)

 

From memory I think they do.

 

Easier backwards as you are already free wheeling.

 

I think what they do is drop the clutch when they hit the ramp with the rear wheels so that there is no traction, something like that.

 

Too early in the morning to think about.

 

Darrell

I dont know. BUT! I bet there was one or two occasions when Evel Knievel wished that ramp was moving when he over shot the bugger? :rofl: