ROTATIONAL MOTION

Chapter 8

Rotational Motion

• How can I utilize radians to measure revolutions?

• How do I describe and measure rotational motion?

Measuring Revolutions

• Degrees: of a revolution

• Radian: of a revolution

• One complete revolution = 2 radians

Radians

Conversions• How many radians is ½ of a revolution?

• How many radians is of a revolution?

• How many degrees is ?

Angular Displacement

• Theta () will be used to describe angular displacement

• Counterclockwise is positive

• Clockwise is negative

Angular Displacement

• d = distance traveled

• r = distance from the center

• = angular displacement

Example

• Lets say you are a gear in Mrs. Howell’s Windstar and you decide to loose two teeth on Highway K. The van limps along until the second broken tooth is reached. What is d between the two broken teeth?

• Theta is • Radius is 0.127 m

Angular Velocity• How fast do gears, CDs, tires etc move?

• = omega = angular velocity

• Unit of measure is radians per second

• t = time

Earth’s Angular Velocity

• If you sat in your chair now until the same time tomorrow, what would your angular velocity be?

Homework•Work sheet

Angular Acceleration• Symbol =

• Measured in rad/s2

Rotational Motion

Quantity Linear Angular Relationship

DisplacementD

VelocityV

Accelerationa

d r

v r

a r

Angular Frequency• Angular Frequency: How many revolutions are completed

in 1 sec

Homework• Page 200• # 1 – 4

Review• Page 200• # 5 – 10• Page 223• # 72 - 77

Lesson Plan• Introduction: Brief intro to radians and angular motion• Day 1:

• Essential Question: slide 2• Input: slides 3, 4, 6, 7, 9• Guided Practice: slide 5, 8, 10• Independent Practice: slide 16

• Day 2:• Input: 12, 13, 14• Independent Practice: Page 200, # 1 – 4

• Day 3:• Review, Page 200 # 5 – 10 and Page 223, # 72 - 77 • Quiz