F1 physics on the moon

[PlasmaBomb]

Originally posted by: Pacfanweb
I'd like to know how you wouldn't accelerate faster on the moon, with all other things being equal except less weight.

On the average car, every 100lbs you take off the car is approximately .1 drop in 1/4 mile time.

So if you have a 400hp car that weighs 3000lbs on Earth, but weighs say, 2500lbs on the Moon but still has the same 400hp, I don't see how it's not going to be .5 quicker on the Moon...maybe even more, since there's less drag from the atmosphere, too.

Read the thread.

It has been explained.

*Counts to 10...*

 

[Pacfanweb]

Originally posted by: PlasmaBomb

Originally posted by: Pacfanweb
I'd like to know how you wouldn't accelerate faster on the moon, with all other things being equal except less weight.

On the average car, every 100lbs you take off the car is approximately .1 drop in 1/4 mile time.

So if you have a 400hp car that weighs 3000lbs on Earth, but weighs say, 2500lbs on the Moon but still has the same 400hp, I don't see how it's not going to be .5 quicker on the Moon...maybe even more, since there's less drag from the atmosphere, too.

Read the thread.

It has been explained.

*Counts to 10...*

I did, and I still don't agree or maybe I don't understand it. Willing to be convinced, though.

Other sports.....jumping, golf, baseball hit, etc....will all go farther with the same force applied to them, because of the lower gravity. (and in the case of a baseball or golf ball, the lower atmosphere helps, too)

A person can jump higher and longer with the same effort, or "horsepower" applied. They still have the same "mass", though. Even more in a space suit, and therefore they couldn't move as freely.

With those facts in mind, if a person can launch 'up' higher and longer with the same power, wouldn't they be able to launch FORWARD longer, too? Because they effectively weigh less, that's why they are able to jump higher......I wouldn't think that only applies if you're trying to move UP.

A one-armed golf shot with a 6 iron went 200yds on the moon. Very restricted movement by the space suit. That's a ballistic arc, somewhat, but with the golf equipment of that day, I'd bet even pros back then couldn't hit a 6-iron on Earth that far with a full swing, much less with one arm.
So that ball went much farther, with less force applied to it.

Explain why that wouldn't apply to a car. We'll say someone paved a drag strip on the Moon, so there are no traction problems, the engine has the exact same HP as on Earth, and the only difference is the gravity. On Earth, gravity helps produce rolling resistance. Tires have more resistance because they are being pushed to the ground with more weight. So you have to overcome all that, plus the mass of the car.
I don't see how the car on the Moon couldn't be at least SOMEWHAT quicker, in the circumstances I outlined.

 

[slugg]

For those that think that less weight = faster acceleration:

You need to realize that there is a difference between weight and mass. A lighter car accelerates faster than an equal, heavier car, not because it's lighter, but because it's less massive. So with 1/6 the gravity, yes, the F1 car will weigh less - but remember that weight has no direct effect on acceleration. The mass of the F1 car remains the same, so it would certainly not accelerate faster.

Essentially, aerodynamic bodies (wings, etc) create the effect of having more weight with zero added mass. That's what aerodynamic downforce achieves. This way, more force is applied to the ground by the wheels, achieving more friction (for harder turning), but not adding any extra mass to move around.

As for cornering, see PlasmaBomb's post. It couldn't be any clearer...

 

[PlasmaBomb]

OK, let us define mass and weight...

Mass = mass, m
Weight = mass multiplied by gravity, mg

When we weigh something on the earth we weigh its weight. For example - take an apple in your hand - what you are feeling is its weight - mg, similarly if you use a spring balance (or any balance) to weight it the extension of the spring is determined by its weight- mg (Hooke's law). However we conveniently refer to it weight in kg, since the force of gravity is (fairly) uniform across the whole Earth. This is where people get confused. What we are really saying is that the object has a mass of 605 kg (in terms of the F1 car) and weights ~ 5935 N.

Newton's laws apply to mass, not weight.

Jumping (simplified) -

A 50 kg man jumps up with a force of 2500N applied for 0.1 second (as soon as he leaves the ground he can no longer exert a force on it).

As already covered F= ma

Impulse is also governed by Newton's first law -
I = Fdt
I = 250

Impulse also equals the change in momentum -
I = delta p = m delta v

Since we know the mass (50kg) we can determine the change in velocity.
delta v = I/m
delta v = 5 m/s

So the man leaves the ground at 5 m/s

Of course as soon as the man leaves the ground gravity begins to slow him down.

To find how high he jumps we need to determine a few things -
At the maximum height he will be instantaneously at rest - velocity = 0

v = u +at
0 = 5 + at
a = gravity
a = -9.81ms^-2 (Earth, deceleration)
-5 = -9.81t
t= ~0.5 s

thus the man jumps -
s = ut + 0.5a(t^2)
s = 5x0.5 + 0.5*-9.81*0.25
s = 2.5 - 1.23
s = 1.27 m

So on the Earth the man manages to reach 1.27 m off the ground.

What is the story on the Moon??

l = lunar gravity = 1.622 ms^-2
a = l
insert into above equations -
v = u +at
0 = 5 + (-1.622)t
t = 5/1.622
t = ~3 sec

s = ut + 0.5a(t^2)
s = 5*3 + 0.5*-1.622*9
s = 15 - 7.3
s = 7.7 m

Summary -
A man that can jump 1.27 m on Earth, can jump 7.7 m on the moon, while exerting the same force, due to the lesser gravity.
So a poor high jumper on earth is an excellent high jumper on the moon

The situation will be the same for the golf ball, as for a given vertical force the ball will have a longer flight time, enabling it to travel further horizontally.

For a race car on earth - again simplified to assume no slippage and sufficient traction to put the power down.

F = 12100 N
Mass = 605 kg
g = 9.81 ms^-2
F = ma
12100 = 605a
a = 20 ms^-2

The race car accelerates at 20 ms^-2 (or approximately 2 g) from a standstill.

On the moon -
F = 12100 N
l = 1.622 ms^-2
F = ma
12100 = 605a
a = 20 ms^-2

On the moon the car accelerates at 20ms^-2 (or ~12 l), again from a standstill.

Edit: Rolling resistance is complicated

Originally posted by: Pacfanweb

On Earth, gravity helps produce rolling resistance. Tires have more resistance because they are being pushed to the ground with more weight. So you have to overcome all that, plus the mass of the car.
I don't see how the car on the Moon couldn't be at least SOMEWHAT quicker, in the circumstances I outlined.

Yes rolling resistance is determined by (amongst other things) weight.

Rolling resistance is determined by the rolling resistance coefficient (Crr) and the normal force applied (force applied at 90 degrees to the surface).

F = Crr x Nf

So assuming the Crr is the same the difference in rolling resistance between a car on Earth and the Moon is 181 N. Which is sod all.

But I have already said that...

Originally posted by: PlasmaBomb
the lesser force should result in a slightly higher top speed due to less rolling resistance

The problem is with less weight and the same aero drag the speed at which you can deploy full power will be higher (due to less grip). This will kill you on the start and also in hairpins.

 

[DivideBYZero]

Wow, here's hoping I never have this discussion in a bar. It would bore the pants off me.

 

[PlasmaBomb]

Originally posted by: DivideBYZero
Wow, here's hoping I never have this discussion in a bar. It would bore the pants off me.

Originally posted by: halik
It would say it would make for slower laps for a couple of reasons:
1) slow corners would get REAALY slow for lack of traction
2) acceleration will suck, again lack of traction
3) top speed will still be limited by aero

Really boring.


The only reason it is so long is because people fail to grasp physics and keep bringing up less gravity = faster.

Plus in a bar it is better to agree to disagree and get back to drinking

 

[Possessed Freak]

But think of the wrecks. More rolls, higher airborne cars, it would just be epic to see the carnage.

 

[PlasmaBomb]

Another point about F1 cars on the moon would be that overtaking would be very difficult, due to the increased dependence on aerodynamic downforce for grip. Once the F1 car got in the dirty air behind another car it would suffer a lot!

 

[exdeath]

Originally posted by: SonicIce

Originally posted by: exdeath
Are we seriously discussing aerodynamics and factoring down force racing on the moon where there is no atmosphere?

Forget the tires and the weight, most of the forces in those cars come from air flow.

The cars would no doubt be faster due to lack of drag, but the turns would have to be several orders of magnitude wider. They would be sliding hundreds of feet sideways all over the place.

Assuming they have air tanks for the engines in the first place.

Also they wouldn't run for more than 5 mins tops before the cooling systems were saturated and unable to dissipate heat without a surrounding medium to carry it away.

Numerous problems here, tire grip is the least of your worries.

lol. op said on the moon with regular earth atmosphere

/facepalm

 

[NAC]

So in other words -
F1 races on Jupiter in the Earth atmosphere would be faster.
F1 races on the Moon in the Earth atmosphere would be slower.

[counting to ten until someone points out that the F1 car would need to be strengthened for higher gravity on Jupiter, etc?]

Interesting? just thought about ants and other bugs. They are incredibly strong & fast for their size. Similar to how F1 cars might be strong & fast for their size compared to giant alien cars on Jupiter.

I could go on? I think I shouldn't?