1. Circular Motion IFP 16 Nov 2015

2. Housekeeping… Lanyards Homework in

3. How do measure angles? Why?

4. Degrees are arbitrary (although convenient) More natural – the radian. The ratio of arc length to radius A more natural measure – the radian r s θ

5. Objectives Explain and use the radian as a natural unit of circular measure Define angular speed and linear speed – relate the two Define and use frequency and period Key Words Radian, degree, angular speed ω, frequency, period So how big is a radian? Work it out…think circumference Some useful conversions

6. Objectives Explain and use the radian as a natural unit of circular measure Define angular speed and linear speed – relate the two Define and use frequency and period Key Words Radian, degree, angular speed ω, frequency, period Speed Angular speed We define ω= θ/t (rad s -1 ) So it is a measure of how fast something is spinning Tangential speed for uniform motion v = s / t

7. Objectives Explain and use the radian as a natural unit of circular measure Define angular speed and linear speed – relate the two Define and use frequency and period Key Words Radian, degree, angular speed ω, frequency, period So we have three equations…

8. Objectives Explain and use the radian as a natural unit of circular measure Define angular speed and linear speed – relate the two Define and use frequency and period Key Words Radian, degree, angular speed ω, frequency, period Time Period and frequency

9. Examples… Bike wheels Cyclotrons

10. Questions…

11. Objectives Explain and use the radian as a natural unit of circular measure Define angular speed and linear speed – relate the two Define and use frequency and period Key Words Radian, degree, angular speed ω, frequency, period Summary… Whiteboards… – Formulae – 3 arcs – What is a radian in degrees (approx)? – So how many radians in a circle (approx)?