2006-10-27 07:21:45 · 9 answers · asked by nima m 1 in Science & Mathematics ➔ Physics
It is the friction that acts against an object that is stationary relative to another object. If you push an object with less force than the force of static friction, the object will not move at all. Once an object starts moving, the friction acting against it is instead called kinetic friction, and it is almost always less than static friction. As a result, a force that was not strong enough to move a stationary object may still be great enough to keep it from coming to a stop.
2006-10-27 07:23:10 · answer #1 · answered by DavidK93 7 · 1⤊ 1⤋
Static friction occurs when the two objects are not moving relative to each other (like a book on a desk). The coefficient of static friction is typically denoted as μs. The initial force to get an object moving is often dominated by static friction.
The static friction is in most cases higher than the kinetic friction.
Rolling friction occurs when one object "rolls" on another (like a car's wheels on the ground). This is classified under static friction because the patch of the tire in contact with the ground, at any point while the tire spins, is stationary relative to the ground. The coefficient of rolling friction is typically denoted as μr.
Limiting friction is the maximum value of static friction, or the force of friction that acts when a body is just on the verge of motion on a surface.
2006-10-27 14:45:34 · answer #2 · answered by hussainalimalik1983 2 · 0⤊ 0⤋
Static friction occurs when the two objects are not moving relative to each other (like a book on a desk). The coefficient of static friction is typically denoted as μs. The initial force to get an object moving is often dominated by static friction. The static friction is in most cases higher than the kinetic friction. Rolling friction occurs when one object "rolls" on another (like a car's wheels on the ground). This is classified under static friction because the patch of the tire in contact with the ground, at any point while the tire spins, is stationary relative to the ground.
2006-10-27 14:24:23 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Limiting friction is not a friction category. It is simply the upper limit of static friction at which point, we have sliding or kinetic friction take over.
Even rolling friction (e.g., tires on the road) is considered static friction because in that instant when the tread meets the asphalt, the two surfaces are at rest with respect to each other. Sliding friction, on the other hand, is based on two surfaces moving with respect to each other.
When a block on a ramp is raised by inclining the ramp, at its limiting friction, the block will start to slide. The sine of the angle of incline (sin(deg)) when the block begins to slide turns out to be the limiting coefficient of friction (k).
Thus, in the equation F = kN, we can find the frictional force (F) if we know the normal weight of the block (N) pushing in perpendicular on the ramp. N = W cos(deg); where W = mg = the weight of the block and deg = the angle of incline for the ramp when the block just starts to slide.
In general, friction is caused by the interaction of electro-magnetic forces from the atoms in the two respective surfaces. However, surface texture (e.g., soft and squishy vs. hard and smooth) can also enter into the values for k. As a consequence, most coefficients are found empirically through experiments similar to the block and ramp experiment just described.
2006-10-27 15:00:15 · answer #4 · answered by oldprof 7 · 0⤊ 0⤋
There are 3 types of friction, Static Friction, Limiting Friction and Kinetic Friction. Static Friction is the frictional force that acts on the object when the object is at rest. Some force might be applied on the object but it remains at rest because of the equal and opposite frictional force. Limiting friction is the maximum value of static frictional force but when the object JUST starts its motion and kinetic friction is the frictional force which acts when the object is already in motion.
2006-10-27 14:37:07 · answer #5 · answered by Chirag Jain 1 · 0⤊ 0⤋
Friction is basically the horizontal force exerted by one surface on another.
It happens because of the interlocking of the uneven projections present of surfaces.
So static friction is the friction that acts between 2 surfaces when the 2 surfaces are not moving.(static means not moving)
and when the surfaces are moving the friction between them is called kinetic friction.(there is also something called limiting friction)
2006-10-27 14:39:47 · answer #6 · answered by jimmy_siddhartha 4 · 0⤊ 0⤋
Static friction (informally known as stiction) occurs when the two objects are not moving relative to each other (like a book on a desk). It happens when both objects are at rest.
2006-10-27 14:32:24 · answer #7 · answered by J 2 · 0⤊ 0⤋
the friction that keeps things sitting still
2006-10-27 14:23:25 · answer #8 · answered by t_roy_e 3 · 0⤊ 1⤋
click here:http://en.wikipedia.org/wiki/Friction
2006-10-27 14:24:15 · answer #9 · answered by Anonymous · 0⤊ 0⤋