Circular Motion
What is the study of objects moving through air called?
Ballistics
Gravity causes planets to orbit the sun, and it causes moons to orbit their planets
What is periodic motion?
Motion that happens over and over again at a regular interval
What is a pendulum?
A weight suspended from a string, chain or pole
What is centripetal force?
The force applied to an object that causes it to move in a circle. Centripetal force pulls towards the center
What must be true in order for a planet to orbit the sun?
a. Forward momentum > force of gravity from the sun
b. Forward momentum = force of gravity from the sun
c. Forward momentum < force of gravity from the sun
b. Forward momentum = force of gravity from the sun
What is oscillation?
Oscillation is movement between two extremes around the mean position
It is also the changing of kinetic and potential energy!
How does object mass affect the period of a pendulum (i.e. how long it takes for the pendulum to make a complete cycle)
It does not. Greater masses can swing at the same rate as smaller masses.
Centripetal force pulls an object towards the center of the circle it moves in, while centrifugal force ________
Pushes the object away from the center of the circle
True/False: Planets revolve around the sun at a constant speed
True! The earth makes its way around the sun in 365.26 days
What is a cycle of periodic motion?
One complete movement
How does the height a pendulum is dropped from affect the period of the pendulum?
It does not, the pendulum will swing at the same rate no matter the height dropped
What kind of momentum does an object moving in a circle have?
Angular momentum
Do planets that are closer to the sun have shorter or longer orbits?
Shorter! The closer a planet is to the sun, the stronger the pull of gravity is. This means the planet needs to move forward with greater speed to be in orbit.
What is the amplitude of a moving object?
Think of a pendulum, what would the amplitude be?
The amount the object moves in each direction around the mean point.
How does the length of the string/pole/chain of a pendulum affect its period?
Longer = slower swing
Shorter = quicker swing
Length is the only factor of a pendulum that impacts its period
If an object is moving around a circle with a radius of 5m, what would happen to the velocity of the object when you decrease the radius of the circle to 2.5m?
The velocity would increase
What is the shape of a planet's orbit?
(Hint: Starts with an E)
Elliptical, planets travel in ellipses
The time for one complete cycle:
a. Amplitude
b. Period
c. Frequency
Frequency is the number of cycles in one second, or the inverse of period
Why can a pendulum be used in clocks?
Because the amount of time of a swinging pendulum does not change even as the size of the swing changes. This predictable period of time lets us keep track of time using the pendulum swings!