Friction Flashcards
what is friction?
Friction is a force that represents the interaction between 2 surfaces. more specifically the force of friction resists motion between the 2 surfaces.
example a basket ball shoe vs the wooden floor
Friction acts in the opposite direction of travel
what is the equation?
Friction is the Magnitude of the
coefficient of friction (u) and the
normal reaction force, (R)
Fm = u R
define coefficient of friction?
coefficient of friction (u) is the frictional force exerted by the SURFACE when the object slide across it
-how easy does an object slide across the surface -ice very easy
-rubber very difficult
greater the U
-roughness of surface
a u value smaller=easy
a u value larger=more difficult
u=0 frictionless
what is the normal reaction force?
r normal force is that is acting perpendicular to the surface
it is the weight of the object acting vertically or perpendicular to the ground
what are the 2 types of frictions?
maximin static fm
which is the maximin amount of friction that can be generated by the 2 surfaces
maximums kinetic
- refers to the most amount of force that can be produced between the 2 surfaces during motion
during kinetic friction there is no __________
Kinetic friction, Fk – occurs when there’s contact between two surfaces during motion
No force applied:
No! applied horizontal force
No! motion
No! friction
FK > FA
when does motion or K kinetic friction occur?
when the applied force Fk is GREATER than static force
what is the formulae for Kinetic friction?
Fk=Uk xRs
What are the factors that influence friction?
R=normal reaction force
u= coeffinet of friction
what is the formulae for static friction?
Coefficient of static friction or s
Fs = Us x Rs
how can Normal force 9R) be altered?
Lubrication
- Wheels
- Reduce R
- Brake pads
- Pulling up on objec
how can U The coefficient of friction be altered? can also be altered to increase
or decrease the amount of friction
slide on wooden floor=wooly socks decrease U
skates =sharp blades= decreaace u
increase u
gloves
wgch is greater UK or Us?
UK beause its motionless
Does greater contact area between two surfaces/ surface area increase friction?
No, friction is only affected by the μ and R (weight)
object on an incline what are the 3 forces?
1) Weight of the block (Fg)
MUST be resolved into Fx and Fy components
Always points down to the center of the earth
2)Normal reaction force
3) (R) – always perpendicular to the surface
4)Frictional force (F)
