Circular Motion: Notes

Question 1

Rotation

Answer 1

Spun about an axis located in the body

Question 2

Revolution

Answer 2

Spun about an axis located outside the body. What this unit is on.

Question 3

Why do you feel like you are being pulled to the right when making a left turn

Answer 3

The centrifugal force pushing against the car door

Question 4

Centripetal Acceleration

Answer 4

Acceleration that points toward the center of the circle

Question 5

Centripetal Force

Answer 5

An object moving in a circle must have a net force acting on it, this is called the centripetal force

Question 6

Where does the centripetal force point?

Answer 6

Toward the center of the circle

Question 7

a_c =

Answer 7

v²/r

Question 8

Period

Answer 8

Time it takes to compete one full revolution
- Either 360^o or 2pi radians

Question 9

a_c (in terms of period)

Answer 9

(4pi²r)/T²

Question 10

As the bucket goes down the circle, tension

Answer 10

Gets bigger

Question 11

As the bucket goes up the circle, tension

Answer 11

Gets smaller

Question 12

Gravity

Answer 12

All objects with mass attract all other objects with mass. Both objects attract each other with equal forces, but opposite directions

Question 13

Why doesn’t the larger object do much accelerating

Answer 13

Because the mass is larger, so looking at F=ma, if the mass is larger, the acceleration will have to be smaller.

Question 14

Equation for gravity

Answer 14

F_g=(GM₁M₂)/R²

Question 15

What does G equal?

Answer 15

6.67 x 10^-11

Question 16

Banked Turns

Answer 16

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

Question 17

Equation for banking angle

Answer 17

tan0 = v²/gr

Question 18

Universal Gravitation

Answer 18

Every body in the universe attracts every other body with a mutual force.

Question 19

Universal Gravity Equation

Answer 19

F_gravity = (GM₁M₂)/R²

Question 20

Which pulls harder gravitationally, the Earth on the Moon, or the Moon on the Earth. Which accelerates more?

Answer 20

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

Question 21

Why doesn’t the moon fall into the Earth?

Answer 21

Because it has too much tangential velocity (like the water bucket)

Question 22

What speed do you need to launch an object for it to orbit Earth?

Answer 22

8 km/s (tangent to the earth)