Brainiacs - What would happen if

[TFU] Thegoon84

[TFU] Thegoon84

[TFU] Thegoon84

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Well its Friday, and not a single **** was given anywhere in the land.... So my brain has been doing over time wonder what would happen:

If a Car lorry was travelling at 70mph with its ramp down, Then a car came behind at say 72mph and began to mount the ramp.... What would happen to the car? Would it accelerate and propel forward as its now taken on an additional speed of the lorry, would it simply cruise on or bounce off/backward?

Anybody?

Happy Friday all!

Also what would chairs look like if our knees bent the opposite direction?
 
* I assume newtons 3rd law would come into play here:
* Weight would also be a factor for the slow down
* The car would continue with the same power applied
* Would the car now be travelling at effetely 142mph
 
It would accelerate once the driving wheels on the ramps due to the change in relative velocity between the two.
 
If the car the driver stops accelerating when it reaches the ramp the car should slowly enter the lorry, unless it loses momentum. If the acceleration continues the car will quickly climb the ramp n cause a crash.
 
Ahhhhh so velocity basically matches conditions and adjusts when there's a change! The cars inertial stops it from accelerating

Which is crazy because the road is a constant just like the ramp.
 
[TFU] Thegoon84;29990597 said:
* I assume newtons 3rd law would come into play here:
* Weight would also be a factor for the slow down
* The car would continue with the same power applied
* Would the car now be travelling at effetely 142mph
Click to expand...

You've slightly mis-interpreted Newton's 3rd law.

You want to consider momentum here more than relative velocities.

The force in question here would not be relative to 72mph + 70mph... it would be 70mph + 2mph and then when the driven wheels of the car touch the ramp, that's when things would change.

The acceleration potential of the car only comes into play when the driven wheels of the car touch the ramp.

Even if those wheels are turning at 72mph... the weight of the car pressing down on them will slow them down quite quickly.

There will likely be a bit of a burst of acceleration when the wheels touch the trailer... but they would quickly slow down and depending on the acceleration potential of the car and how hard the accelerator is depressed... in general, I wouldn't expect the car to gain more than 5-15mph on top of the speed of the lorry.

I'm sure a half-decent driver could get the car in the back of the truck without much difficulty.
 
crinkleshoes said:
You've slightly mis-interpreted Newton's 3rd law.

You want to consider momentum here more than relative velocities.

The force in question here would not be relative to 72mph + 70mph... it would be 70mph + 2mph and then when the driven wheels of the car touch the ramp, that's when things would change.

The acceleration potential of the car only comes into play when the driven wheels of the car touch the ramp.

Even if those wheels are turning at 72mph... the weight of the car pressing down on them will slow them down quite quickly.

There will likely be a bit of a burst of acceleration when the wheels touch the trailer... but they would quickly slow down and depending on the acceleration potential of the car and how hard the accelerator is depressed... in general, I wouldn't expect the car to gain more than 5-15mph on top of the speed of the lorry.

I'm sure a half-decent driver could get the car in the back of the truck without much difficulty.
Click to expand...

Thank you, that's answered a life long question of mine! haha.

But yes you are totally correct, I was gobsmacked how easy the car roll onto the back of the truck!
 
The road passing under the wheels is doing so at 72mph the ramp will be passing the wheels at 2mph, the closing speed. Due to the way gearing works there will be relatively very little torque being produced at the wheels so as the meets the ramp and leave the road the inertia of the rotating mass of the car will very very quickly be overcome and I'm fairly sure the car would stall after a small chirp of the tyres.

Doing this at say 32mph in second you could probably get some speed up on he ramp due to the torque at the tyres being considerably higher.
 
crinkleshoes said:
There will likely be a bit of a burst of acceleration when the wheels touch the trailer... but they would quickly slow down and depending on the acceleration potential of the car and how hard the accelerator is depressed... in general, I wouldn't expect the car to gain more than 5-15mph on top of the speed of the lorry.
Click to expand...
How much of a slowing effect would the angle of the ramp have?
Obviously some, compared to the level road (assuming the council have laid a decent surface)...
 
When the driven wheels of the car hit the lorry if the clutch isnt dropped the car is going to jolt forward and possibly do damage to itself.

Think of it like holding a car in the air engine revving and wheels spinning then dropping it flat on the ground.
 
[TFU] Thegoon84;29990662 said:
Thank you, that's answered a life long question of mine! haha.

But yes you are totally correct, I was gobsmacked how easy the car roll onto the back of the truck!
Click to expand...

I missed the mythbusters video posted a few posts back :)

MeEsH BaKkA said:
The road passing under the wheels is doing so at 72mph the ramp will be passing the wheels at 2mph, the closing speed. Due to the way gearing works there will be relatively very little torque being produced at the wheels so as the meets the ramp and leave the road the inertia of the rotating mass of the car will very very quickly be overcome and I'm fairly sure the car would stall after a small chirp of the tyres.

Doing this at say 32mph in second you could probably get some speed up on he ramp due to the torque at the tyres being considerably higher.
Click to expand...

Yeah... in a manual car if the driver was to leave it in 5th/6th gear when going on to the ramp, there's a good chance the engine would stall.

You'd have to dump the clutch just before hitting the ramp and drop it into a much lower gear.

A lot easier in an automatic.

ttaskmaster said:
How much of a slowing effect would the angle of the ramp have?
Obviously some, compared to the level road (assuming the council have laid a decent surface)...
Click to expand...

The same as any incline / hill / driveway of a similar angle.

If not careful, the car could easily roll back off the ramp onto the road.
 
adolf hamster said:
When the driven wheels of the car hit the lorry if the clutch isnt dropped the car is going to jolt forward and possibly do damage to itself.

Think of it like holding a car in the air engine revving and wheels spinning then dropping it flat on the ground.
Click to expand...

Not necessarily. Depends on what gear the car is in, how much momentum it has, etc. If the car's in top gear and low revs it'll simply stall.
 
Goon, where in Swansea do you live?

I want to witness you putting the theory to test :D
 
I reckon we all chip in and buy a flatbed and a RWD car. I'll chip in a tenner and nominate EVH to drivethe car.
 
Diddums said:
Not necessarily. Depends on what gear the car is in, how much momentum it has, etc. If the car's in top gear and low revs it'll simply stall.
Click to expand...

Possibly, i was thinking more the shock of the system.

Used to be big into rc cars and a lot of them have "slipper clutches" that are designed to stop you from blowing up the drive system if you land a jump with the wheels spinning full pelt, although i had a collection of blown driveshafts for the baja that proved that either that system or my driving wasnt working.
 
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