[adr3naline fix]

Here's a weird thought


most likely a stupid one, but a thougth none the less

Say your coming up to a drop off a ledge at your local mall. Its about 10 ft tall, To flat. (yeah, you know you've done OR thought about it. Maybe both?) If you went 5 mph and dropped that 10 feet about 8 feet out, as opposed to going 20 mph (LOL) to the flat, landing about 15 to 25 ft out, which would be the harder hit?


Maybe it's just that I'm tired. Maybe someone slipped me a pill into my redbull. Mabye I'm retarded, but this question has been in my mind for the last 15 min. lol


Any thoughts?

 

[Changleen]

Going faster DOES make a given drop less hard. Simple physics.

 

[-dustin]

wait a minute...i swear there was a big ass thread a long time ago saying speed into a drop had nothing to do with impact.

 

[Changleen]

As someone who has dropped quite a few drops in their time, I promise you it does.

 

[syadasti]

Same hit (*hit?) regardless of forward speed but, more stability at speed due to greater forward momentum.

 

[Reactor]

Speed doesn't change the force the bike hits the ground with, you drop the same distance, the same gravity etc.... However, speed gives the bike and rider more momentum, which can help smooth out obstacles.

 

[CrabJoe StretchPants]

forces in the vertical direction are not effected by a horizontal velocity, so the impact will be equivalent in force. however, like syndasti said, greater horizontal velocity will create greater momentum, which will aid in the stability while landing.

 

[Changleen]

No, Force = Mass * acceleration. With a higher forward momentum, your change in vertical acceleration is lower (than gravity), therefore the proportion of the force is lower. Remember by moving horizontally you are already battling gravity to an extent.

 

[BurlyShirley]

Going faster DOES make a given drop less hard. Simple physics.

WRONG.

 

[Wumpus]

No, Force = Mass * acceleration. With a higher forward momentum, your change in vertical acceleration is lower, therefore the force is lower. Remember by moving horizontally you are already battling gravity to an extent.

You better reread your physics book.

 

[Changleen]

Pish. The faster, the smoother the landing = Yes.

 

[syadasti]

The hit from the drop in either case is equal to the potential energy due to gravity - ie always the same. The difference in speed at which you hit the drop means you'll have more or less kinetic energy and forward momentum when you hit the ground.

 

[JRogers]

You better reread your physics book.

word. going faster does seem to smooth it out, but that's not because you're hitting the ground any slower vertical speed-wise

 

[Jeremy R]

Doing Drops to Flat at your local mall has its own Physics equation.
Its like when you multiply by zero then you always get zero.
Except doing drops to flat at the mall you always multiply by GHEY.

You can talk physics all day, but you always feel the drop less when you hit it at speed.

 

[maxyedor]

Speed won't change it, however speed changes how far out you hit, and that changes the angle at wich you hit. So in a round about way speed does affect it.

 

[nmjb]

No, Force = Mass * acceleration. With a higher forward momentum, your change in vertical acceleration is lower (than gravity), therefore the force is lower. Remember by moving horizontally you are already battling gravity to an extent.

Based on F=Ma you are going to generate more horizontal force the faster you go. BUT acceleration due to gravity is constant, therefore making your vertical force constant, regardless of your horizontal speed.

 

[Changleen]

Exactly, there is less change in momentum at speed.

 

[syadasti]

You can talk physics all day, but you always feel the drop less when you hit it as speed.

That's cause there are two vectors acting on you instead of one - you don't have to depend on your balance, your forward momentum helps you out.

 

[Jeremy R]

That's cause there are two vectors acting on you instead of one - you don't have to depend on your balance, your forward momentum helps you out.

Balance does play a big part in it for sure, that is what I meant by "feel."
Even if your suspension compresses the exact same amount, you still feel it less at speed.

 

[Changleen]

That's why it's possible for BMXers to do 30+ft drops to flat over huge gaps without destroying themselves and exploding their bikes.

 

[adr3naline fix]

these are exactly the kinds of reactions I thought this thread would get. I get a slight feeling of accomplishment when that happens. haha

(not the arguing but the different physic aspects)


I don't really have an input on the suject since I just charge hardcore and only worry about the grandma that just came out the mall entrance with her shopping car. lol


Good info guys

 

[Jeremy R]

That's why it's possible for BMXers to do 30+ft drops to flat over huge gaps without destroying themselves and exploding their bikes.

Or either they are just totally fookin insane and/or did not get enough hugs growing up.
Watching them makes my wrists ache.
True badasses.

 

[ALEXIS_DH]

Going faster DOES make a given drop less hard. Simple physics.

to flat?
i dont think so.

proof 1) the vertical vector remains unchanged.
proof 2) delta of momentum is the same over the same time interval.

to slopes, the delta of momentum happens over a longer time interval (because you are going down as you land). easier than vectors.

 

[adr3naline fix]

Or either they are just totally fookin insane and/or did not get enough hugs growing up.
Watching them makes my wrists ache.
True badasses.

yeah I cant understand how they can do all these insane gaps without occasionally breaking a wrist or ankle just because of the impact. true talent. true badasses. lol

 

[Changleen]

to flat?
i dont think so.

proof 1) the vertical vector remains unchanged.
proof 2) delta of momentum is the same over the same time interval.

You are right. The vertical component of the force is the same, but as a proportion of the total momentum it is reduced the faster you go. Hence the faster, the smoother at speed = Yes.

 

[syadasti]

You are right. The vertical component of the force is the same, but as a proportion of the total momentum it is reduced the faster you go. Hence the faster, the smoother at speed = Yes.

Same vertical vector though just less downward resultant the faster you go. The resultant you feel is closer to horizontal the faster you go. If you just step off the drop the resultant vector you feel is the vertical vector (speed and KE is zero).

Most people probably think it feels better to keep moving forward than to be smashed into the ground

 

[Changleen]

The resultant you feel is closer to horizontal the faster you go.

That's what I'm trying to say...

 

[Radarr]

More speed = smoother.

Now, for everyone who was asleep during physics, or who got their e-physics classes out of the way in 2 minutes by finding and printing themselves a certificate: When you shoot a bullet out of a gun, and drop a bullet of the exact same mass/caliber at the exact same time from the exact same height as the chamber, the two bullets will hit the ground at the exact same time (ignoring wind/changes in air pressure or temperature, etc.).

That being said, when you ride your bike off a cliff, no matter what your speed at the top, your Y (vertical) component of velocity will be the same when you hit the ground. Whether or not you are moving in the X direction at 0.1 mph or 10000 mph, it doesn't matter. You still hit the ground with the same amount of force in the Y direction.

Is it easier to ride your bike when you are going fast versus going slow? Of course it is. You gain stability with speed, especially with 8" of travel front and rear, low BBs, and a slack headtube angle. Although it may feel smoother, you're still absorbing the exact same amount of energy when you hit the ground. One is just easier to deal with.

 

[SkaredShtles]

So in other words the landing at speed will be smoother, but there will be an equal chance of the bike breaking into a million pieces.............

 

[Radarr]

So in other words the landing at speed will be smoother, but there will be an equal chance of the bike breaking into a million pieces.............

Actually, when you're going fast, there's a much greater chance of breaking the bike. Thus, when you approach a drop or jump of any type, get off of your bike and walk down the hill. Don't even take your bike, as it might spontaneously burst into a pillar of flames.

 

[allsk8sno]

next time we ride together i am following you so i can watch this pillar of flames, maybe my bike will live up to its name..

 

[SkaredShtles]

<snip> Thus, when you approach a drop or jump of any type, get off of your bike and walk down the hill.

This actually is how I approach most drops and jumps.

 

[Radarr]

next time we ride together i am following you so i can watch this pillar of flames, maybe my bike will live up to its name..

Nah, its probably too heavy to catch on fire.

You coming this way next weekend? I should have 360s down by then...

 

[HaveFaith]

Speed won't change it, however speed changes how far out you hit, and that changes the angle at wich you hit. So in a round about way speed does affect it.

Exactly.

 

[beestiboy]

More speed = smoother.

Now, for everyone who was asleep during physics, or who got their e-physics classes out of the way in 2 minutes by finding and printing themselves a certificate: When you shoot a bullet out of a gun, and drop a bullet of the exact same mass/caliber at the exact same time from the exact same height as the chamber, the two bullets will hit the ground at the exact same time (ignoring wind/changes in air pressure or temperature, etc.).

That being said, when you ride your bike off a cliff, no matter what your speed at the top, your Y (vertical) component of velocity will be the same when you hit the ground. Whether or not you are moving in the X direction at 0.1 mph or 10000 mph, it doesn't matter. You still hit the ground with the same amount of force in the Y direction.

Is it easier to ride your bike when you are going fast versus going slow? Of course it is. You gain stability with speed, especially with 8" of travel front and rear, low BBs, and a slack headtube angle. Although it may feel smoother, you're still absorbing the exact same amount of energy when you hit the ground. One is just easier to deal with.

Finally someone making sense....if you need proof put a zip tie on the fork and perform the drop at different speeds and measure the compression of your fork. Higher loads theortically would cause the shock to compress more.

The stability you all refer to is the gyroscopic forces of the wheels (come on I cant be the only person to do the holding the spinning wheel while standing on the lazy susan). These forces increase with velocity hence when cruising faster the drop feels smoother.

 

[cannondalejunky]

i'm not gonna read all of the reply's u still drop at the same speed no matter what your forward speed is

 

[JRogers]

When you shoot a bullet out of a gun, and drop a bullet of the exact same mass/caliber at the exact same time from the exact same height as the chamber, the two bullets will hit the ground at the exact same time (ignoring wind/changes in air pressure or temperature, etc.).

Wait, are you agreeing with this statement?

 

[johnbryanpeters]

...The stability you all refer to is the gyroscopic forces of the wheels...

We have a winner! Changleen, don't try building nuclear reactors, please.

 

[Skookum]

Whoah! For a second there i thought i stumbled into MTBR....

 

[golgiaparatus]

Your falling at the same speed either way. Drop will be the exact same vertical impact.