Rotational Motion

Question 1

Equation: Uniform Circular Motion

Answer 1

v = 2 * π * r / T
Note: essentially (distance / time)
T = period

Question 2

time required for an object to travel once around the circle
time required for a wave to make one complete cycle (inverse of frequency)

Answer 2

Period (T)

Question 3

Equation: Circumference of a circle

Answer 3

2 * π * r

Question 4

The ______ vector is constantly changing direction and is tangent to the circle of motion

Answer 4

velocity vector
(Object is accelerating even if magnitude of velocity stays the same b/c it is always changing direction)

Question 5

Acceleration is always pointed to the _____________ of the circle.

Answer 5

inside of the circle

Question 6

The Velocity vecotr in uniform circular motion is constantly changing direction and is ______ to the circle of motion

Answer 6

tangent

Question 7

Equation: Centripetal Force

Answer 7

F(c) = m * v^2 / r

Question 8

What provides the centripetal force for an object of mass (m) being twirled at the end of a string?

Answer 8

F(tension) on the string creates the Centripetal force

Question 9

Equation: Time for a mass in centripetal motion to make one revolution

Answer 9

t = 2 * π * r / v

Question 10

2 typical uses for Centripetal force equation

Answer 10

find the velocity given the force

find the force required to sustain uniform circular motion given a certain velocity

Question 11

Equation: Centripetal acceleration

Answer 11

a(c) = v^2 / r

Question 12

The acceleration vector in centripetal acceleration always points toward the ______ and constantly changes direction as the object moves.

Answer 12

center of the circle

Question 13

Equation: Centripetal Force

Answer 13

F(c) = m * v^2 / r

Question 14

Equation: Torque

Answer 14

Torque = F * L
Note: F = magnitude of force
L = lever arm
SI Unit: N * m

Question 15

Torque is positive if it tends to produce a _______ rotation about the axis.

Answer 15

counterclockwise

Question 16

Torque is negative if it tends to produce a ____________ rotation about the axis

Answer 16

clockwise

Question 17

distance from the axis of rotation to where the force acts on the object at 90º

Answer 17

level arm (L)

Question 18

for objects that are of uniform density, the__________ is at the geometric center of the object. For objects that are of nonuniform density, the _______ shifts toward the region where most of the mass is concentrated.

Answer 18

center of gravity

also called center of mass