Note: Content may be edited for style and length. Science News. Journal Reference : D. Berman, S. Deshmukh, S. Sankaranarayanan, A. Erdemir, A. Macroscale superlubricity enabled by graphene nanoscroll formation. A hover puck. In advance, obtain two battery-operated hover pucks for the class demonstration.
Have you ever tried to run as fast as you can on a track? Pretty easy, huh? Now think about trying to run that fast on a frozen pond, or a hockey rink. Not so easy, huh?
Friction is the force between our shoes and the ground that helps us run, whether it is on the track or on the rink. Which surface do you think has the higher frictional force? If you are thinking the track, you are absolutely correct!
The larger frictional force helps our shoes stay in contact with the track longer, allowing us to use our muscles to push off the track and run fast. The smaller frictional force on the hockey rink does not allow our feet to stick to the rink, making us slip and, most likely, fall on the ice.
A good way to think about friction is that it is the force that impedes motion. When you roll a ball on the ground, the force that makes it eventually come to a stop is friction. When the ball is in contact with the ground, the kinetic energy of the ball in motion is transferred to heat. Now that seems kind of odd doesn't it, we can make heat just by rolling a ball on the ground. Why don't people in Alaska just roll balls on the ground to keep their houses warm? The reason is that the heat produced is hardly enough to detect, although it is present.
As your hands move back and forth, they have kinetic energy. Because your hands are touching, there is also some frictional force between them. This friction converts the kinetic energy of your moving hands to heat.
Are you still rubbing? Can you feel your hands warming up? Now touch your hands to your face, the heat you feel was created by the force of friction! Can you imagine a world without friction? While we cannot eliminate friction, we can limit its power significantly. Remember the rolling balls in Alaska? What if those balls were rolling on a waxed floor? Now the energy you put into the system by rolling the ball will not be lost to friction on the floor, and can be transferred to the pins at the end of the alley.
Bowling is based on this principle; in this case, we do not want the ball to slow down on the lane so that it can knock over the most pins at the end of the lane. We can also simulate a frictionless world with the use of these two hover pucks. Show the hover pucks to the class and then proceed with a demonstration. If it is not possible then why not?
And if it is possible, are there any current examples? This can apply to both kinetic and static friction. The bloc could be made to inject liquid helium under its own base. The best real-world example of near-zero but not zero coefficient of friction is for the case of wet ice sliding on wet ice. For everyday materials, ice has the unusual property of melting under pressure. This means that when two blocks of ice are pressed together, the local contact points of highest pressure melt into water and the interface between them soon smooths itself down and becomes a thin layer of water at almost zero degrees C.
The friction force that one block can exert on the other then is set by the viscosity of the water in the interface, which is low, and the blocks slide over each other with almost zero effort. Relatively low friction is also got on an everyday basis with hydrodynamic bearings, in which a constant flow of lubricating oil is pumped into the small space between two parts that are rotating against each other- for example, the connecting rod that is clamped to the crankshaft in an automobile engine.
In this case, the oil pressure "levitates" the two sliding surfaces out of contact with each other and both are then slipping on a thin layer of oil.
Teflon-on-teflon also creates a very low friction system if the teflon surfaces are sufficiently smooth. How do you move on a frictionless surface? Can we move without friction? What if something has no friction? What if there was no friction for 1 minute?
What would be easier to do without friction? What happens if there is too much friction? What problems can friction cause? What are 3 factors that affect friction? What are the factors that affect friction Class 8? Is friction affected by mass? What type of friction occurs when objects are not moving? Can friction dangerous? Where is friction useful?
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