Is friction applied when you're in the air? or is that air resistance or something else?
157431
They may call it friction but it's a misnomer.  There is skin friction, of course, which dissipates energy as heat, but much of the drag force is caused by imparting kinetic energy to the air mass, i.e., shoving it out of the way.  If you were shoving all the air downward that force would be called lift.  That energy may eventually be dissipated but it is theoretically recoverable. Friction dissipates energy as heat immediately.
981131
Sliding friction is the friction that an object has while it's moving.\n\nAn eraser has the most sliding friction.\n\nStatic friction is the resistance of an object from movement. I suppose since an eraser has the most sliding friction, it will also have the most static friction. that or a paperback book just because it's heavier.\n\nit really depends on the coefficient of friction. \n\nI should say that the eraser will have the highest coefficient of frictions, but the paperback book will have the highest overall friction just because of it's weight.
91362
It's tranferred to heat/friction from the impact
66741
Rubber in contact with other surfaces can yield friction coefficients from 1.0 to 2.0.\n\nhttp://en.wikipedia.org/wiki/Friction
783057
What I said about inclined surfaces works just the same on a horizontal surface; you will compute sin(theta)=0 and cos(theta)=1 so the normal gravity force=g*m and there is no gravity force parallel to the surface.\nWhen KE or PE decreases due to friction energy loss, the decrease equals the friction energy loss which is friction force * distance. I assumed you already knew that. If my answer helped I'm happy. I'd appreciate it if you go back to that question and select my answer as best; this is the normal procedure even though it would eventually be selected by public vote.\nP.S. A tip on yahoo answers. I only found this question by accident. You can add followup questions to your original question; just click on the original question and there should be a link that lets you add more words, probably called Additional Details. That's what I was referring to when I said I'd be checking for followup questions.
32662
actually the limiting friction is greater than kinetic friction.  it takes more force to overcome the forces of the limiting friction(start the object moving) then it does to overcome kinetic friction(keep the object moving). this makes sense logically, once the object is sliding, it's easier to keep it sliding then it is to start it moving in the first place...
918757
because the moistness causes friction
1175019
In general resistance increases.If there is no turbulence then it can be shown that viscous drag on a spherical moving body of radius r and velocity v is \n6*pi*(eta)*r*v\nwhere eta is coefficient of viscosity.\nTherefore air resistance is usually taken as directly proportional to velocity.\nHowever in real life things are not that simple.With turbulence various other forces come in play.Surprisingly it can reduce the air drag too.Though it may cause deviations in path as forces are no longer just opposite to velocity .
400487
Wind resistance acts as a force which opposes the motion of the feather down to the ground.  The feather's weight acts to accelerate it downward.  You have two opposing forces, one is constant (the weight), the other depends largely on the speed of the feather falling (wind resitance).\n\nThe feather will intially start out accelerating downward due to gravity at -9.81 m/s^2, but as its velocity increase, the opposing force increases aswell, eventually reached an equilibrium with the feather's weight and the object stops accelerating.  Just because there is no acceleration doesnt mean there is no motion, the feather will continue to fall at a constant velocity after the wind resistance has increased enough to counter act the wieght (net force = 0, acceleration = 0).\n\nnet Force = mass * acceleration
696645
Nice trick, combining multiple questions into one. I'll answer one q, no. 3.\nThe 300N force along the slope doesn't contribute to the normal force so has no effect on friction. The normal force is m*g*sin(slope) = 100 * 9.81 * 5/20. Your picture\nhttp://i34.photobucket.com/albums/d130/MATTRAINES/q4.jpg?t=1164668264\ndoesn't give a value for coefficient of friction, so if we assume it's 1, then Ff = the normal force.
587906
Whether friction force depends on velocity or not depends (further) on what sort of friction you are considering.\n      Friction between a solid-solid interface is seldom affected by the relative velocity of the bodies. There, in fact, the force merely depends on the NORMAL reaction on the surface. For fluids, however, friction is substantially affected by the relative velocity. You may check out "NEWTON'S HYPOTHESIS" & "STOKE'S LAW" in this context.
133048
Hello, \n\nThis problem is a bit more involved than you might initially think. There are 4 major considerations you must take into account. First, the acceleration is dependant on the angle of the hill at any given time. Therefore, acceleration is NOT constant, rather fluctuating with the incline. Second, the wind resistance is NOT constant by any means. It increases exponentially with the speed of the sled. Third, the force of the kinetic friction is not constant either. While the coefficient of friction does increase somewhat with speed (you could use an average for this), you cannot neglect the increase in friction when the sled goes around a corner. As you know, the friction is based on the normal force of the sled. At 90mph, the centripetal acceleration around a curve is V^2/r (V=velocity, r is radius of corner) which becomes quite considerable, even though steel on ice only has a kinetic coefficient between .01 - .05. \n\nNow that I have bored you out of your mind, the full equation would look something like this (I’m writing everything longhand so you know what I’m talking about)\nSum of the forces = mass x gravity x sin(angle of hill) – [(coefficient of friction) x mass x gravity x cos(angle of hill) – mass x velocity ^2 / radius of curve] – (Force of air drag)\n\nNotice the term included to account for curves: – mass x velocity ^2 / radius of curve\nDrops to zero when they are going in a straight line (r = infinity). \n\nTo find your acceleration (at a specific point in time), you simply divide everything by the mass of the sled and there you go!\n\nPS. don't take physics advice from dental students ;P
845875
Ah, time to dig out the physics from last year.  If I remember correctly:\n\nStatic friction is when the force of friction is greater than the force applied; thus basically what amount of force it takes to move the object from rest.\n\nKinetic friction is when you apply a force for an object to keep sliding.  In this, it "breaks free" of your push and continues sliding.\n\nAnd the force needed to initially break the static friction (to get it moving) is much more than what is needed to keep it going.\n\nHope this helped a bit.  Just remember that static friction is associated with objects at rest and kinetic is objects in motion, and don't get the two mixed up. :*P\n\nHave fun with physics!
1024834
compression and friction
609398
FRICTION is the energy generated when two bodies have some physical interaction with each other. \n\nGRAVITY is the force of a mass which pulls an object towards its center.
65207
mck\n14 hours ago\n\nReport Abuse\n\n\nIt is true that gravity increases the velocity of a falling object. However, there is also air resistance, which slows an object down while it is falling. This is dependent on a number of variables, one of which is the current velocity of the object. Therefore, as gravity causes the speed to increase, air resistance causes it to not increase as fast. At a certain point, the *terminal velocity* is reached, which means that the raindrop cannot speed up (because of air resistance) and cannot slow down (because of gravity).\n\nIf you actually mean why it doesn't hurt because of pressure, that's because a raindrop is "soft" - it can change shape when it hits your skin. However, freezing rain, although small, can hurt (I know from experience). Again, the velocity isn't great enough for it to actually puncture the skin (usually). \nSO the main causes r terminal velocity and air resistance.
1144696
gravity and air resistance.