playersnoopy

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playersnoopy last won the day on July 14

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  1. You bring up a very good point... also I probably misspoke in terms of the loss of friction in respect to the change in the normal force. I will say there's parts I am not very well versed when it comes to the artificial gravity experienced in circular motion so I will make statements clear when I am making assumptions and personal opinions here. One thing to note is that first it's the increase in weight experienced by the rider not necessarily the increased in weight of the bike and the rider. That's not to say the weight gain isn't significant; I just don't know how much... best case let's say only the wheels cause the centripetal acceleration and with the good suspension the rest of the bike and rider experiences the 1g laterally, but can't be the full weight of the bike no matter what right? (assumption). The other thing to note is I based it purely based on a horizontal flat surface of the road; where in a banked turn you definitely can go faster. So even with the lateral g-force how much of it is affecting it in the vertical direction to affect the normal force perpendicular to the road surface to the tire; how much is the vertical component. Assuming CG is same is the lateral g-force horizontal and parallel to the ground? But yes the friction lost should/could be negligible even on a flat surface. Regardless like I said you are correct I shouldn't have mentioned the friction part; as the centripetal force is what really causes the loss of friction with the velocity component being squared which is why we go slow (even though amount of friction may not have changed?).
  2. 1. Need to understand how bikes turn to know that you're right hanging off doesn't make a difference; the steering and lean affects how a bike turns. But there seems to be a misconception on why we "need" to hang off the bike and some assume it's to cause "less" lean angle rather than to offset the balance to "keep" the bike in its turn. I'll cover the science of it later as it is a lot of info -.- But in short more lean angle the less steering angle for the same radius of turn needed; this is the most important factor to understand. Which is why you can always turn a bike by counterweighting; but this is a little harder for sportbikes than say dirt bikes or flat track riders who in fact counterweight to lean the bike. When hanging off in a turn you can let off the handlebars (a little and safely) and see the bike maintain its lean throughout the turn. Take a rider off the bike for analysis (watch youtube videos of idiots falling off their bikes doing wheelies and the bike remains upright but coutersteers by itself back and forth; due to Newtonian laws) and we see that the bike would countersteer back to the opposite if we don't apply additional forces to prevent it. 2. This is subjective; but for sportbikes you can only counterweight so far before the bike will just fall to the ground unless you're going fast enough where the centripetal force keeps you up. You can also lean into the turns upright and lean with the bike as most DMV manuals says to do when at speed. But now the topple over effect is again raised because you essentially become a tall lever; and the greater the distance of the lever from the fulcrum the less force required to torque the lever. So basically easier to topple over plus it's harder to balance yourself upright for continuous turns on sportbikes. Hanging off brings your Center of Mass/Center of Gravity (CM/CG) both same in this case lower and makes the bike more balanced in the turn. 3. Similar to 2 when talking about dirt bikes or lighter bikes counterweighting is easy; bring a 400lbs bike into play it's very hard to balance the weight when you weigh half the bike or less. 4. Proper steering techniques steers the bike; position comes into play depending on how fast you go. Try counterweighting at 80mph on a sports bike -.- 5. Should be self explanatory if you accept response to 1
  3. I'll try and explain it the best that I can. First in any engineering physics class covering classical mechanics involving circular motions will state in the book Centrifugal "Force" in quotes usually or at least call it a fake/false force. Second is to understand reference frames and in classical mechanics we use non-inertial reference frames. Take an example of you standing in the back of a pickup truck doing 50mph and throwing a tennis ball off the back away from the direction of travel; and you throw this ball say 20mph. Now you the thrower of the ball observe it clear as day moving in the opposite direction from the direction you're travelling... and at a rate of 20mph (which is correct in reference to you and the truck)... now take an observer standing off to the side of the road looking perpendicular to the road and he sees the ball still moving in the direction of the travel of the truck and you just at 30mph (which is also correct in reference to the observer). But which is "correct"; now ignore air resistance and gravity to the mix as we're not trying to calculate the rate of decrease of the speed and arc of the motion and so on... we're applying ideal physics to understand the parts we want to figure out what's going on. So in circular motion for an inertial reference frame one common example is that of you sitting on spinning disc (say a merry go round) and releaseing a ball on the disc and observe it in an outward motion; it's best to actually see it in effect to see how weird things get in difference reference frames... here's a video showing some non intuitive things occurring in that situation The biggest mistake the average person that doesn't have a lot of background in physics and just reads up on some aspects of it when researching circular motion is applying Newton's laws of motion incorrectly in an wrong reference frames; you probably heard people saying well yes there is this inward force called centripetal force but Newton's law says there is an equal and opposite force when not accelerating to give a net 0 force and that force is the centrifugal force. Only correct when in the inertial reference frame for this circular motion example. Another non intuitive mistake made is that almost all of us have been in a car at some point, and taken a turn or a curve, and we swear we are being pushed outward from the curve and that is the centrifugal force we "feel". But it's actually inertia you're feeling. Let's say you're in the passenger seat; on this turn (left turn) you are pushed to the door and say I'm going outward. But in fact the car is moving inward left turn; and you are still moving forward; so naturally you hit the door. So analyze a motorcycle taking a turn (left turn again); you know at any point you were only going straight and you added input to turn left and lean to the left. You can say you "feel" and outward force but analyze where did this magical outward force come from; we know the downward force is from gravity (which is mysterious in itself). When you lowside the bike and rider don't all of a sudden end up moving "outward" of the turn; they end up sliding forward (minus any weird tire contact of the wheel causing a different motion) but you get the idea. That's about the simplest way I can try and explain it.. but you want to apply physics in the discussion from text and online sources; majority of it will be from classical mechanics which is all non-inertial reference frames. A lot of people don't understand that part and apply intuition to the mix and confusion erupts. I plan on posting up some videos on some of the physics misconceptions after I review CSS when I go for lvl 1+2 next week. Personally I think a lot of the youtube instructions out there like ridesmart and individuals would do a lot better just explaining "do this to get this result" and leave out the why part; seems like 90% is accurate and then 10% is made up physics interpretation on their part and discredits the 90% they just got right.
  4. Sorry to chime in on this just a pet peeve... Let's go by stating there is no Centrifugal force. Just centripetal force, which goes inward to the center of a radius of a turn, no outward force. And please don't mention inertial reference frames, if you know what that is then you know it doesn't apply here and just trying to be difficult. And you can't just rotate the picture 45 degrees and assume forces rotate like that, gravity doesn't rotate with you so the direction of forces can't be right. In physics the direction of the bike lean angle does matter because that DOES change the magnitude of the forces. You lean 45 degrees, for simplicity say the CG is at 45 degrees, then the normal force applied to the tire would be COS(45)*N which is why you have less friction at lean than upright. A lot of good info on the discussion mixed with bad physics. You can do more explaining what you need to do to make something happen and only apply the science behind it if it's what really is happening not what we think is happening.
  5. Sorry to hear that... maybe next time. I'm booked for those dates and booked a room nearby so I can be well rested. Hope to run into some people I ride with in DMV.
  6. The question is brought up in almost every engineering physics class when we cover friction. Homework question is usually something along the lines of "If force of friction is only dependent on the coefficient of friction and the normal force" then why do race cars have bigger tires than your average car?" You can even see this question in MIT's open course on Physics covering friction available at MIT site or youtube... I kinda speculate my professor lectured based on theirs. The answer is and has always been... "Pressure", those that have bicycles at some point you probably experienced a blow out... usually because the pressure exerted on the tire was too great. It's also why you use lower tire pressure when on the track compared to the streets. Unlike the streets you don't have stop and go traffic and the tires heat up (which raises pressure), and heat up a lot, more horsepower and heavier the bike the more pressure. Ways to handle this is by compound of the tire, contact patch, initial cold pressure, and of course use larger tires.
  7. Anyone going to CSS Monday July 31st for Level 1, and/or August 1st for Level 2 at New Jersey Motorsports Park in Millville? I'll be coming up from Rockville, MD and staying up there from Sunday evening til Tuesday.