GRAVITY DOES NOT PULL YOU FORWARD!!!!!!!!!!

tank wrote:

Its quite obvious that gravity is a downward force perpendical to a plane. The question is if that downward force, that energy, can be used to increase forward momentum. I have read no clear refutation of that being impossible.

Is it really that difficult a concept? The only way that the perpindicular force of gravity (or potential energy) can be used to increase forward momentum is if the center of gravity ends up lower than when it started. Unless you have an infinitely long downward slope, that is not possible indefinitely.

In terms of running on a relatively flat surface (or at least not one that is infinitely downwards sloping) it is rather difficult to maintain any kind of normal running mechanics when your center of gravity continually gets closer to the ground with no countering application of force to raise it back up.

well articulated

My collegue Doctor Stupid is quite correct on this matter.

Additionally, it's highly concerning that a guy with a Ph.D (the Pose guy) could propogate something as ridiculous as "gravity pulls you forward."

Memnoch (Michael) wrote:

You are an idiot

Gravity is a vector force

That is a redundancy; all forces are vector quantities. And the fact that gravity is a vector doesn't mean that it can pull you in any direction that suits your moronic arguments about running form. The Earth's gravity has one direction only - straight DOWN.

YOU are the idiot, as is anyone else who agrees (openly or otherwise) that gravity can pull you forward.

tank wrote:

Its quite obvious that gravity is a downward force perpendical to a plane. The question is if that downward force, that energy, can be used to increase forward momentum. I have read no clear refutation of that being impossible.

Maybe I wasn't clear way back so allow me to elucidate. Gravity will not produce a net increase in your forward momentum, assuming you are running across a smooth non-inclined surface. Momentum is the product of velocity and mass. The gravitational force vector is always orthogonal to a level running surface, and therefore, the velocity (and hence momentum) produced is in that direction (i.e., perpendicular-down to your direction of travel). What DOES happen is that in mid-stride your center of mass is slightly higher than at push-off. Your velocity/momentum vector has two components, one straight ahead, and a much smaller one straight down caused by gravity. You cannot consider this a gain, however, because you purchased it by propelling yourself slightly upward during the push-off phase in order to compensate for the eventual drop. (Consider that if you didn't do this, your center of mass would have to get lower and lower with each stride as you must by necessity drop somewhat during mid-stride due to gravity.)

So, although one might describe the situation (inaccurately) as "falling forward", this is balanced by an "upward push" on the push-off phase of the stride. Seeing that the system will not be 100% efficient, it would be sensible to limit the amount of vertical displacement involved in each stride. One way to do this is to use a faster turnover. There would of course be a point of diminshing returns where further increases in cadence would create greater losses than those saved by decreasing the vertical displacement.

Jhuffman wrote:

Doctor Stupid,

It seems that you are frustrated. Are you self prescribing medication again. Don't take out your anger on the POSE METHOD, it is merely a most ideal model with which to help you learn to run with maximam efficiency, so you will be less likely to get an injury and thus learn to run faster. If you can't understand how and why you should imploy this technique into your running style it is okay don't panic. Just continue to run the best you can. Best of luck!

You have been proven wrong. Yet, you continue to dessiminate information that anyone with a basic knowledge of physics can tell is incorrect. Do you believe that it is responsible to tell atheltes thing that are incorrect?

craptacular wrote:

A really good way to prove your "law" would be for you to run as fast as you can, then trip. Right under you would be a nice soft pillow, five feet away would be chuck norris. If your law is correct, you would fall imediately to the ground on to the pillow. If it is somewhat flawed, then you would land right in the clutches of mr chuck norris. As far as I can see, that is the only way of ever ending this conundrum.

False. You have initial velocity in the horizontal plane due to the fact that you were running when you tripped.

newton wrote:

the fact is gravity CAN cause an object to fall forward, but there is a difference of concept between the direction gravity pulls and the resulting motion, which may be directionally constrained. a good example of this is the upside down pyramid with a center of gravity slightly off base. initially at rest, the pyramid will start to fall forward in the presence of gravity. gravity is the only thing causing the object to fall forward since in the absence of gravity the pyramid will remain in position. however that is not to say that gravity pulls forward. gravity pulls the center of mass straight down, however the only way the COM can move down is if the pyramid rotates forward. the 2nd force vector in the equation for this case is the vector perpendicular to the arc that the COM follows on its fall forward.

IE Changing potential energy into kinetic. Also, you could picture a ball at the top of a 'half-pipe'. Simply let go, and it will gain speed, MOVING FORWARD, with no forces acting on it besides gravity and a normal reaction force from the half pipe. How is this any different from running downhill? You're changing gravitational potential into kinetic energy.

asdef wrote:

How is this any different from running downhill? You're changing gravitational potential into kinetic energy.

But unless you have an infinite downwards slope, you will need to regain that lost altitude by the application of a vertical force greater in magnitude than gravity.

There is no such thing as a free lunch.

The question was whether or not gravity could pull you forward or not, yes? This shows that it can. Also, if there is any net downhill, then you use gravity to your benifit.

asdef wrote:

The question was whether or not gravity could pull you forward or not, yes? This shows that it can.

No it does not. Gravity always pulls straight down. You can apply additional forces (whether it be in the forward direction pushing off from your feet or around a fulcrum like the rotating inverted pyramid) in order to achieve forward motion.

Also, if there is any net downhill, then you use gravity to your benifit.

Obvious, since you have given up potential energy. Now how efficiently you are able to translate that potential energy into forward motion is dependant on things like your running mechanics.

I guess my interpretation of the statement is, "Can ravity, in the normal running environment, pull you forward?" Thus, such things as a ground and reactionary forces are present. Speaking strictly of gravity and no reactionary forces, then, no, it can't "pull you forward".

damn, i thought everyone wrote formulas on their palms in college.

Lets think clearly about this and not over complicate and obfuscate the critical issues.

Can gravity enhance forward momentum?

Although gravity is a downward force it can under some circumstances be redirected into forward motion. The examples given by others including the ball in the half pipe, upsidedown tipping pyramid, rollercoaster are all examples of this. Its specious to try and refute this by stating that the forward momentum is all due to energy expended by having previously lifting the object. All gravity created velocity is due to previous energy used to lift the object (stored enegy).

In the examples given the objects move faster forward due to the force of gravity.

No one has refuted that the upside down pyramid falls forward faster due to gravity.

Please don't obfuscate that basic observed fact with miss directed application of common formula's.

newton wrote:

if you could imagine an object orbiting the earth and then a sudden cessation of earth's gravitational field the object would fly off on a tangent, still moving forward. if it was gravity that was pulling the object forward the object would simply come to a complete stop in the absence of gravity. and if you could imagine the momentum of the object suddenly disappearing the object would fall straight down. it is the combination of gravity and momentum that causes an object in orbit to move the way it does.

So does that mean that when you drop a ball from a cliff, if gravity ceased to act on that ball before it touched another mass (ie, the ground) then the ball would stop moving in midair?

Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

You know, it's threads like this that allow me to understand the mindset that jailed and tortured people for saying things such as the Earth is not flat and revolves around the Sun. A little science goes a long way to light a pervasive darkness. Stop thinking with your gut people, and use your brain.

Question for Einsteins - What actually is momentum? What is that invisible force still acting upon an object which causes it to stay in motion?

How does gravity act upon objects millions of light years away instantly? By what mechanism does this occur?

How is space actually warped by gravity? Does it become increasing warped the closer you get to create the sense of falling?

let's add a treadmill-is-easier-because-it-helps-you-bring-your-foot-backwards theme

JimFiore wrote:

You know, it's threads like this that allow me to understand the mindset that jailed and tortured people for saying things such as the Earth is not flat and revolves around the Sun. A little science goes a long way to light a pervasive darkness. Stop thinking with your gut people, and use your brain.

tank wrote:

Its specious to try and refute this by stating that the forward momentum is all due to energy expended by having previously lifting the object. All gravity created velocity is due to previous energy used to lift the object (stored enegy).

What's specious is redefining the problem. Everyone here agrees that given potential energy (PE), one can increase velocity in a direction normal to the force of gravity through translation of PE into KE (kinetic energy). This is not the argument. The argument is whether one can increase the net efficiency of running on a level surface through some application of this principle. The answer is no. NET efficiency includes the "buy" of the initial PE. You cannot ignore this in a closed system. The only way you will get a boost is by running downhill and not having to run back up the hill.