Download Chapter One Notes

Uniform
Circular
Motion
https://www.youtube.com/watch?v=KvCezk9DJfk
What is a circle?
In geometry: the set of all
points in a plane that are
at a given distance from
a given point.
What is a circle?
In physics: All points
whose position vector
has the same beginning
and the same length in a
plane.
Radial Position Vectors
p
p
Uniform Circular Motion
•Constant speed
•But not
constant velocity
•The velocity is always
changing direction
Uniform Circular Motion
Velocity vector
is perpendicular
to position
vector.
It’s a tangent.
v
p
Uniform Circular Motion
 Period - the time it
takes to go around
the circle once
 Symbol - T
Uniform Circular Motion
Acceleration
vector is
perpendicular
to velocity
vector and
pointed to
center of circle.
v
ac
centripetal acceleration
(ac)
“center seeking”
Uniform Circular Motion
Use geometry’s similar triangles:
ac =
2
v /r
ac = centripetal acceleration
(m/s2)
v = velocity (m/s)
r = radius of circle (m)
Uniform Circular Motion
centripetal force
Fc = mac
Fc = centripetal force (N)
m = mass of object (kg)
ac = centripetal acceleration (m/s2)
Uniform Circular Motion
v
centripetal
force
Fc = mac
https://www.youtube.com/watch?v=DLgy6rVV-08
Fc
Sample
A 1.6 kg object travelling in a circle has a
centripetal acceleration of 9.0 m/s2. What is
the centripetal force acting on the object?
Given
Unknown
Equation
Substitute
Solve
Work Your Turn
Problems
https://www.youtube.com/watch?v=ID0R43My4Co&index=8&list=PLZHDrmpjw4My79MFX9azRSkG9hXTP2FNJ