Chapter 16: Circular Motion Flashcards
How are angles measured in this section?
Radians
arc length expression
rθ
Degrees to Radians
radians = (π x degrees) / 180
Angular Velocity
angle at object rotates through per second
Angular velocity equation
ω = θ/t
How can angular velocity be expressed?
magnitude of angular velocity can be written in terms of the magnitude of linear velocity
equation linking linear and angular velocity
v = ωr
Frequency
number of complete revolutions per second
Period
time taken for a complete revolution
angular velocity for a complete circle
ω = 2π/T
angular velocity in terms of frequency
ω = 2πf
Centripetal Acceleration
car accelerating but not going any faster, as constantly changing direction
centripetal acceleration in terms of linear velocity
a = v^2/r
Centripetal acceleration in terms of angular velocity
a = ω^2 r
Centripetal force
circular motion caused by a constant net force perpendicular to velocity, no work is done on the object, KE is constant
centripetal force in terms of linear velocity
F = mv^2/r
centripetal force in terms of angular velocity
F = mω^2 r
How can you investigate circular motion
using a rubber bung, some washers, some string and a clear plastic tube
Method to investigate circular motion
Measure the mass of the bung and mass of the washers
Thread the string through the plastic tube
Make a reference mark on the string, measure from mark to centre of the bung
mark up with the top of the tube, spin the bung in a horizontal circle
Measure time taken to make a complete circle
Use equations to find angular velocity and centripetal force
Repeat for different r, radius of bungie path
True or False: The centripetal force and velocity of an object moving in a circle are always in the same direction
False
Velocity is always at a tangent to the circle, force along the radius, they are perpendicular
True or False: An object moving in a circle at a constant speed is not accelerating
False
Direction is always changing hence velocity is always changing, hence accelerating
