University Physics: Mechanics Ch6. Friction Lecture 9 Dr.-Ing. Erwin Sitompul .
Friction in Physics
Transcript of Friction in Physics
FRICTION IN PHYSICS
BY : MAY RAPIKAID : RSA1C312006
WHAT IS FRICTION ?
APPLICATION OF FRICTION
EXAMPLE PROBLEM
KINDS OF FRICTION
WHAT IS FRICTION ?
FRICTION IS FORCE THAT OPPOSING THE MOTION OF TWO SURFACES IN CONTACT
f = N
APPLICATION OF FRICTION
EXAMPLES…
WHEN WE WALK WHEN THE CAR IS BRAKED
KINDS OF FRICTION
FRICTION STATIC
FRICTION KINETIC
FORCE THAT WORK WHEN THINGS HAVEN’T
NOT MOVED
fs =
FORCE THAT WORK WHEN THINGS MOVED
fk =
EXAMPLE PROBLEM
PROBLEMS
An object with mass = 10 Kg in rough floor pulled by force F = 25 N to the right. If the coefficient of static objects with the floor is 0.2 with kinetic coefficient 0.1. Determine :a. Normal Forceb. Acceleration of the motion of object
mF
SOLUTION
a. Normal Force
N-W = 0 N- mg= 0 N- 10Kg(10m/s2) = 0 N = 100 N
m
N
F
W
f
b. Acceleration (Second Newton Law) Fx = ma f = fk = F-f = ma = 0.1 (100)25-10=10a = 10 Na= 15/10a= 1.5 m/s2