Circular Motion: Notes Flashcards
Rotation
Spun about an axis located in the body
Revolution
Spun about an axis located outside the body. What this unit is on.
Why do you feel like you are being pulled to the right when making a left turn
The centrifugal force pushing against the car door
Centripetal Acceleration
Acceleration that points toward the center of the circle
Centripetal Force
An object moving in a circle must have a net force acting on it, this is called the centripetal force
Where does the centripetal force point?
Toward the center of the circle
ac =
v2/r
Period
Time it takes to compete one full revolution
- Either 360o or 2pi radians
ac (in terms of period)
(4pi2r)/T2
As the bucket goes down the circle, tension
Gets bigger
As the bucket goes up the circle, tension
Gets smaller
Gravity
All objects with mass attract all other objects with mass. Both objects attract each other with equal forces, but opposite directions
Why doesn’t the larger object do much accelerating
Because the mass is larger, so looking at F=ma, if the mass is larger, the acceleration will have to be smaller.
Equation for gravity
Fg=(GM1M2)/R2
What does G equal?
6.67 x 10-11
Banked Turns
Usually it is friction between the car tires and road that allows a car to make a turn. However, roads can be banked to reduce the need for friction
Equation for banking angle
tan0 = v2/gr
Universal Gravitation
Every body in the universe attracts every other body with a mutual force.
Universal Gravity Equation
Fgravity = (GM1M2)/R2
Which pulls harder gravitationally, the Earth on the Moon, or the Moon on the Earth. Which accelerates more?
They both pull on each other with the same amount of force, but because the moon has a much smaller mass than the earth, the moon’s acceleration is larger
Why doesn’t the moon fall into the Earth?
Because it has too much tangential velocity (like the water bucket)
What speed do you need to launch an object for it to orbit Earth?
8 km/s (tangent to the earth)
