Darius11 12 #1 November 6, 2003 Ok I was really good in school and physics was my best subject. Ivan if this has been posted already sorry. According to Newton’s law of gravity all items fall at the same rate. For example if you drop a peace of paper and a bowling ball in a vacuum they will hit the ground at the same time at the same speed. Now here is the question? I keep on hearing people say that the heavier you are you fall faster. I am 5”11 and 245lbs. I was told we must have hit the 140MPH as you all know that is faster then terminal velocity at normal altitude. Now what makes the difference is the air but the way air works is if there is more surface there is more resistance, therefore a bigger person should fall at a slower rate. Please someone explain this to me. I know Newton was not wrong but I have heard every one say that you will fall at a faster rate if you are heavier. Sorry for the bad writing skills English was never my best subject.I'd rather be hated for who I am, than loved for who I am not." - Kurt Cobain Quote Share this post Link to post Share on other sites
Hooknswoop 19 #2 November 6, 2003 Same reason a bowling ball has a higher terminal velocity that a soccer ball. Density and surface area of the object and denisty of the air it is falling through determine terminal velocity. Derek Quote Share this post Link to post Share on other sites
Darius11 12 #3 November 6, 2003 Ok then why is it that in a vacuum a feather and a bowling ball hit the ground at the same time? Also why is it you can pass a tennis ball to each other in free fall. Hey maybe I am missing something but a bowling ball and a feather don’t have the same density.I'd rather be hated for who I am, than loved for who I am not." - Kurt Cobain Quote Share this post Link to post Share on other sites
marks 0 #4 November 6, 2003 your not going to be able to pass a tennis ball to somone in freefall unless you fill it with lead first Quote Share this post Link to post Share on other sites
greybeard 0 #5 November 6, 2003 Its magic dude! The spirit of the skydiver defies all laws and floats the soul. Believe! Quote Share this post Link to post Share on other sites
skybytch 273 #6 November 6, 2003 Freefall isn't a vacuum. Quote Share this post Link to post Share on other sites
Darius11 12 #7 November 6, 2003 Ok i am just going with what i have seen people do in free fall. The lead would explain it. I'd rather be hated for who I am, than loved for who I am not." - Kurt Cobain Quote Share this post Link to post Share on other sites
ReLLiK75 0 #8 November 6, 2003 Yep....and I guess a common misconception is that termainal velocity is some magic set number, but it isn't. Your own terminal velocity will vary depending on whether you're freeflying or belly flying. Terminal velocity is just what it says--the velocity where you no longer accelerate. __________________________________________ Have you Got Flare? Quote Share this post Link to post Share on other sites
sundevil777 102 #9 November 6, 2003 A bigger (fat) person does have more drag due to their size, but the effect of the extra weight is more than the extra drag. An extra 20 lbs of beer belly can actually make you more streamlined, if that was where mother nature decides to put all your extra beer weight.People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am Quote Share this post Link to post Share on other sites
Amazon 7 #10 November 6, 2003 If we were ALL jumping on the moon... no problem we would all fall at the same rate... of course the parachute would not work worth a shit.. but its a vacum. The reason is simple my dear... Tall skinny people.. BIG WINGSPAN... ratio of weight to surface area of flight surfaces...large...fall slow....AKA Floatybutts Short round people..SMALL WINGSPAN..ratio of surface area to flight surfaces small.. FALL FAST.... hence the name.... Anvil Club members Quote Share this post Link to post Share on other sites
marks 0 #11 November 6, 2003 QuoteOk then why is it that in a vacuum a feather and a bowling ball hit the ground at the same time? no resistance... no air.... QuoteAlso why is it you can pass a tennis ball to each other in free fall you cant.. unless you can fall really really slow... QuoteHey maybe I am missing something but a bowling ball and a feather don’t have the same density. if you take resistance. "air" out of the equation. then density does not matter when it comes to the speed it will fall.... Quote Share this post Link to post Share on other sites
Hooknswoop 19 #12 November 6, 2003 QuoteOk then why is it that in a vacuum a feather and a bowling ball hit the ground at the same time? Because there is no air resistance, only gravity, which acts on all ogjects equally. QuoteAlso why is it you can pass a tennis ball to each other in free fall. Because it has been filled with weight in order in crease it's density without increasing it's surface area. QuoteHey maybe I am missing something but a bowling ball and a feather don’t have the same density. Right, which is why they have different terminal velocities in air. Derek Quote Share this post Link to post Share on other sites
Darius11 12 #13 November 6, 2003 Yes i know. But the way air works is you have more resistance if you have more surface. And the way the human body works is if you are heavier you have more surface therefore more resistance to gravities pull. Please someone who is a physicist help. I have been thinking about this for about 3 months nowI'd rather be hated for who I am, than loved for who I am not." - Kurt Cobain Quote Share this post Link to post Share on other sites
skybytch 273 #14 November 6, 2003 I'm not a physicist, but I can do a search..... Quote Share this post Link to post Share on other sites
indyz 1 #15 November 6, 2003 Quote But the way air works is you have more resistance if you have more surface. And the way the human body works is if you are heavier you have more surface therefore more resistance to gravities pull. This is somewhat of a simplification, but I think it gets the concept across: What is the ratio of the skydiver's weight to his surface area? Does a man who is 6 feet tall and 300 pounds present twice as much surface to the wind as a 6 foot tall, 150 pound man? Of course not. Surface area does scale linearly with weight. Plus, the fat man's gut will actually make him more aerodynamic than a guy with a flat stomach in a belly-to-earth orientation. Quote Share this post Link to post Share on other sites
Darius11 12 #16 November 6, 2003 Now I get it. A heavier item or person has more momentum and more force or energy so it pushes the air at a faster rate there for achieving a higher speed. Thanks I finally get it.I'd rather be hated for who I am, than loved for who I am not." - Kurt Cobain Quote Share this post Link to post Share on other sites
Hooknswoop 19 #17 November 6, 2003 QuoteBut the way air works is you have more resistance if you have more surface. And the way the human body works is if you are heavier you have more surface therefore more resistance to gravities pull. Adding weight increases weight without adding surface area. Putting on 20 lbs. is not going to be compensated for by enough area to keep the same terminal velocity. the added weight increases terminal velocity more than the added surface area slows you down, net result is a faster terminal velocity. Derek Quote Share this post Link to post Share on other sites
Samurai136 0 #18 November 6, 2003 ok. here it goes. All objects are subject to the same acceleration due to gravity (9.8m/s/s) I am the same height as you but I weigh 100 lbs less. You and I present roughly the same surface area to the wind on our belly. Air resistance of an object increases w/ speed. The faster it falls the more air resistance there is for the object. Air resistance, as a force, is acting in the opposite direction to the force of gravity. Your mass(in kg) is 111.13kg My mass is 70kg F=ma force equals mass times acceleration The force you experience at exit= 1089 newtons of force due to gravity. The force I experience at exit= 688.94 newtons of force due to gravity. Terminal velocity is the speed at which the force of air resistance counters the force of acceleration due to gravity. At terminal you are no longer accelerating, you are falling at some constant speed. Your terminal velocity will be higher than mine because you will have to fall faster to counter the greater force. That is the simplest explaination. Ken"Buttons aren't toys." - Trillian Ken Quote Share this post Link to post Share on other sites
leroydb 0 #19 November 6, 2003 Quote...the way the human body works is if you are heavier you have more surface therefore more resistance to gravities pull. begin "heavier" does not equal a faster fall rate if 2 people weigh 200 lbs, but one is 6 feet tall and the other is 5 feet tall; then the tall guy would fall slower than the short guyLeroy ..I knew I was an unwanted baby when I saw my bath toys were a toaster and a radio... Quote Share this post Link to post Share on other sites
Darius11 12 #20 November 6, 2003 Thank you all i finally get itI'd rather be hated for who I am, than loved for who I am not." - Kurt Cobain Quote Share this post Link to post Share on other sites
pilotdave 0 #21 November 6, 2003 QuoteNow I get it. A heavier item or person has more momentum and more force or energy so it pushes the air at a faster rate there for achieving a higher speed. Thanks I finally get it. Momentum has nothing to do with it. Force, well, sorta. Forget body shape for a minute. Just think of 2 identical people but one ate a bunch of lead for breakfast and weighs more without having a different shape. Gravity exerts a force on each body. The one with more weight will have more pull from gravity. Thats by definition of weight actually. Anyway, both people, at a given fallrate, will generate the same amount of drag. At the lighter person's terminal velocity, the drag on him will exactly match his weight. That's why he stops accelerating and holds that speed. The heavier person will have the same amount of drag at that speed but he'll still have more weight than drag. He won't stop accelerating until his drag matches his weight. Drag increases with velocity. The faster you fall, the more drag you produce. Technically drag is related to velocity squared but that doesn't matter. Body size and shape really complicates the issue. It's VERY difficult to estimate how body shape will affect fallrate. Now, we know a guy with a big belly is going to be heavy so it's pretty obvious he's going to fall faster than a skinny person, but it's very much not obvious what the exact affect the shape his stomach will have on his fallrate. Aerodynamics are a lot more complicated than it sometimes looks. Hope this helps. Dave Quote Share this post Link to post Share on other sites
pilotdave 0 #22 November 6, 2003 If you people would use a unit of weight instead of mass, you wouldn't have to deal with F=ma. Dave Quote Share this post Link to post Share on other sites
Samurai136 0 #23 November 6, 2003 He said he took physics so I stuck w/ the basic Highschool formula and kept it metric Ken"Buttons aren't toys." - Trillian Ken Quote Share this post Link to post Share on other sites
BikerBabe 0 #24 November 6, 2003 QuoteMomentum has nothing to do with it. errr...if you want to be truly technical, it does. The exact statement of Newton's 2nd Law is: F=dp/dt, or the change over time of the object's momentum. Momentum: p = mass * Velocity. If mass is assumed to be constant, you get the familiar F=m*a. OK, in our cass, mass is probably constant, but I'm being picky. I'm a nerd. Never meddle in the affairs of dragons, for you are crunchy and taste good with ketchup! Quote Share this post Link to post Share on other sites
pilotdave 0 #25 November 6, 2003 Don't gotta bring newton in! He just tells me how much I weigh but I don't really care if I'm sweating in freefall and losing mass cause the fat guy is prolly sweating even more! Dave Quote Share this post Link to post Share on other sites
