There is some serious confusion going on here between acceleration and speed/velocity. The acceleration of any falling object will be equal to gravity; so how can a buggy 'look' as though it is accelerating 10 times faster than it is? You may be able to convince me its velocity appears increased, based on car lengths.

I think your main flaw is that you are trying to compare/factor dimensioned units (some of which are constant, like gravity). I suspect the only way to achieve a true comparison (assuming it is even possible) would be to use non-dimensional parameters.

These are probably just a happy coincidence (remember you've scaled velocity by a factor 'derived' from acceleration).

.... then again, I could be completely wrong. This is just my feeling.

edit: nevermind, misread :p

Exactly. If you're looking at a film of a car, which has no other clues to the size, then your brain would assume that it's about "car-sized", i.e. about 4 m long.

It will then make further assumptions about how fast it should be able to move, i.e. how many car-lengths it can cover in one unit of time - either from a standing start, or at full speed.

Based on that argument (and yes, I know not everything will scale - air is a fixed density, etc) then if you scale is time, velocity/acceleration follow.

I just think it would be interesting to try to produce a video where the cars appear to move like cars, not ferrets on speed...

I see where you're coming from, I just don't think it will work. But that could be because I already know how a model car looks/behaves. You may be able to 'trick' somebody who's never seen one though.

Whilst I'm doubtful I would also be interested to see someone's attempt at it.

:)

A further thought:
Your idea may be quite effective under some conditions (e.g. when travelling on the flat), but when falling it wouldn't look right because our model cars already accelerate under gravity in the same way a full-size vehicle does (i.e. in this instance you don't need to slow it down, assuming the track/obstacles are to scale).

No...

The effect when falling is exactly the same. From the top of its flight (i.e., zero vertical velocity) the car will accelerate downwards at 10 (okay, 9.81) m/s^s. So, in 0.5 sec, both cars will fall (1/2 a t^2 =) 1.25m.

For the 1:1 car, that means it's fallen roughly its own height. The 1/10th car will look as though it's fallen 10 times as far - unless you slow it down.


I find it's something which is really noticeable in films with CGI, where they haven't got the gravity / acceleration quite right - there's a monster the size of a bus, and I'm left thinking "it just can't leap like that".

Ten times as far compared to what? If you have no other references whatsoever (which you suggested earlier), then your brain won't know how big the vehicle is and therefore no idea what a car length is.

Assuming the track is approximately to the same scale as the model vehicle it will already be falling with the correct apparent acceleration; so no slow down will be necessary in that situation.

You can't have it one way and not the other.

There are many variables at play and simply adjusting one, i.e. time, isn't going to have the desired effect - in my opinion.

The easiest way to settle this would be to make a video, slow it down, and then rub my face in it when you prove me wrong :lol:

The height thing would only apply if driving the buggy over real car sized obstacles, since jumps are scaled down to our cars. :)

So a 1/10th scale car when compared to 1/1 car doing the same speed travels its own length 10 times as fast.

So when using the time a car takes to travel its own length as a cue for speed, a 1/10th car at 30mph looks like a 1/1 car at 300mph.

So if you want a video of a 1/10th car to look like a video of a 1/1 car, the speed and acceleration looks 10 times faster, why not slow the video down by 10? Why would you slow it down by the root of 10?

Hello!
I'm glad you like my video.:)

Here is anonther one at the Swedish Nationals.

http://www.youtube.com/watch?v=AJN8qwMm9gc

/Mr. Pink

Awesome wheelie off the line. Awesome mayhem. Keep up the good work!

The first corner has a substantial amount of comedy value.:thumbsup: It was probably very different at full speed but in slow motion it looks almost pathetic.:D
Great video, keep'em coming.:)

Because real cars don't do 300 mph. This is my whole point - the speed doesn't scale like that. A 1/10th buggy doing 30 mph looks like it's going faster than a Formula One car or a Bugatti Veyron, which is just wrong for an off-road car.

Ah well - like Dunc said, would someone please do a video at ~1/3 speed?

Okay I see your point :).