how fast would an SV go around the TT ?

Because 10 cubed is 1000....

Originally Posted by MiniMatt

Because 10 cubed is 1000....

so it would need 1000 cubic horsepowers?

That's what I thought was a little iffy - your formula where the factor of speed is cubed and then applied to the power rather than the initial "cube your power to double your speed" looks a lot closer to me.

Told you I'd forgotten my physics

Originally Posted by Flamin_Squirrel

Well thats... completely wrong really.

E=mc2 tells you how much energy matter has if you convert that matter into pure energy. So unless your SV has an atomic engine that equation has no meaning in this context what so ever.

As speed increases, power requirements are cubed (not squared). So, all things being equal, to double your top speed you need 8 times the power.

Well, thats.... completely wrong really.

E=1/2 m.v2 - so to double your speed you;ll need 4 times the energy. Before taking windblast etc into account of course.

EDIT - Unless of course your cubed factor takes into account windblast, friction etc, in which case you're cleverer than me and i'll shut up However, i'd be interested in knowing where you got that formula, and how it's arrived at.

Originally Posted by jonboy99

Well, thats.... completely wrong really.

E=1/2 m.v2 - so to double your speed you;ll need 4 times the energy. Before taking windblast etc into account of course.

EDIT - Unless of course your cubed factor takes into account windblast, friction etc, in which case you're cleverer than me and i'll shut up However, i'd be interested in knowing where you got that formula, and how it's arrived at.

No I'm not wrong at all.

That formula you've given is for calculating kinetic energy, not power.

Power = Energy / Time

Time = Distance / Velocity

So...

Power = Energy * Velocity / Distance

Power = 1/2 * Mass * Velocity^3 / Distance

Back to school for you

I like your working, but are you then saying that power is proportional to top speed?

*Edit* no, obviously not, which is where the whole velocity cubed thing came into it - BUT I think your equation relates to acceleration, and not top speed at all. Ie what the speed will be when x amount of power is used to accelerate to a certain velocity in a set distance. It would also ONLY apply to an ideal world with no friction or wind resistance, when in fact these two factors are pretty much the entirety of what governs top speed, along with aerodynamics.

*Looks at all the calculations and physics stuff*

Hey, I wonder if a plane on a treadmill would fly or not .....



*runs*

Lol haha i remember that discussion!

I'm going to stick my oar in too...


The two issues of acceleration and top speed can get confused.

1) Acceleration is rate of increase of velocity. But Kinetic Energy increases with v^2 . Power is a rate of energy, so Acceleration is proportional to the square root of power. Going from 0 to 50 mph takes as much of an increase in energy as going from 50 to 71.

2) Top speed is mainly (I think) limited by wind resistance. This is proportional to v^3 . Don't ask me why, fluid / aero dynamics is complicated. Top speed is proportional to the cube root of power. Comparing between bikes is a bit rough, as their aerodynamic factors will obviously be different. But for a given bike this can show what a power increase will do to your top speed. ie not much.

The actual affect of bikes topping out is a combination of both factors. Each further mph costs more energy than the last one, plus the wind resistance rapidly becomes significant, no matter how tiny it seems at lower speeds.

Originally Posted by mac99

..

Beat me to it ...

Its air resistance.