Do now: Tūrei, 15 Mahuru 2015 Fun Clips: Awesome Mini Bike Loop Globe of Death Progress test...
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Transcript of Do now: Tūrei, 15 Mahuru 2015 Fun Clips: Awesome Mini Bike Loop Globe of Death Progress test...
Do now:Wednesday, April 19, 2023
Fun Clips:
Awesome Mini Bike Loop
Globe of Death
Progress test tomorrow:
Everything so far:
Centre of mass, momentum
Circular motion
Homework
Today’s Kaupapa:Wednesday, April 19, 2023
1) What is the difference between rotational motion and circular motion?
2) What is a radian?
3) Why do we use radians?
4) Converting between radians and degrees
1) Clear your calculator memory
2) Calculate: sin30o =
3) Calculate: sin-1(0.7071) =
Everyone: Wednesday, April 19, 2023
Discuss in pairs:Wednesday, April 19, 2023
1) What is the difference between rotational motion and circular motion?
2) What is a radian?
3) Why do we use radians?
Three types of motion:1) Translational (COM moves in straight lines)2) Circular (COM orbits a central point)3) Rotational (spinning around the COM)
http://d24w6bsrhbeh9d.cloudfront.net/photo/a6w9eB8_460sa.gif
What is a radian?
Great animation:
1) How would you describe this in words?
2) How would you describe this mathematically?
Board notes
Radians:In general:
= d / r
(or d = x r)
d is the distance travelled around the arc of a circle - measured in metres is the “angular displacement” - measured in radians
A ferris wheel turns through 6 revolutions.a) What is the angular displacement of the wheel?b) What distance does a person riding on the ferris wheel move if the radius is 10m?
Why do we use radians?For rotational motion, displacement d and velocity v depend on the radius of rotation
But both points move through the same angular displacement and have the same angular velocity
Angular Velocity• Measured in radians per second (rad s-1)• Symbol (omega) not w (double u)
t
Average angular velocity = angular displacement
time taken