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Chapter5 Friction, Circular Motion, Drag Force, NG HUI YUN A20SC0187 -…
Chapter5
Friction, Circular Motion, Drag Force
Friction Force
perpendicular to normal force
independent of surface area in contact and sliding speed
Kinetic Friction
Static Friction
Uniform Circular Motion
object moves in circle at uniform speed
v and a always perpendicular to each other
centripetal/radial acceleration
T = 1/f
T = time for one revolution
f = number of revolutions per second
v=rω
ω=2πf
v=2πrf
v=2πr/T
ω=angular velocity
r=radius of circle
centripetal force
(second law) radial component
Highway Curve
centripetal force
-force supplied by friction between tires and pavement
tires skid out of circular path if static friction is insufficient
μs points towards centre of circle
μk opposes direction of motion
Banking curve reduces skidding
There is a speed for which no friction at all
Nonuniform Circular Motion
a =
Both are perpendicular to each other
magnitude of a =
if drag force ∝ velocity,
object slows down until drag force = Fg,
object falls with (constant) terminal velocity,
that is
NG HUI YUN
A20SC0187
