2.1 Circular Motion Introduction

Question 1

What is angular displacement?

Answer 1

angle through which a point has rotated in a given direction

Question 2

Equation for angular displacement?

Answer 2

Ø = s/r 
where 
Ø = angular displacement (rad) 
s = arc-length (m) 
r = radius (m)

Question 3

Does angular displacement have units?

Answer 3

No it is just an angle

Question 4

What do we measure angular displacement in?

Answer 4

Radians

Question 5

What is 360 degrees in radians?

Answer 5

2𝛑

Question 6

What is 90 degrees in radians?

Answer 6

1/2𝛑

Question 7

What is 45 degrees in radians?

Answer 7

1/4𝛑

Question 8

What is 1 radian approximately in degrees?

Answer 8

57 degrees

Question 9

What can we use to describe how quickly an object is moving in a circle?

Answer 9

revolutions per time frame (seconds or minutes)

Question 10

What is this?

Answer 10

angular velocity (in oscillations referred to as angular frequency)

Question 11

What is angular velocity? (definition)

Answer 11

The angle an object rotates through per second

Question 12

Equation for angular velocity?

Answer 12

ω = θ/t 
where  
w = angular velocity (rads^-1)
θ = angle (angular displacement) (rads)
t = time (seconds)

Question 13

What else can we say angular velocity is?

Answer 13

The rate of change of angle in rads

Question 14

Can this equation be used for both average and instantaneous velocity?

Answer 14

yes

Question 15

What is the equation for linear velocity using the equation for angular velocity?

Answer 15

v = rω 
where 
v = linear velocity(ms^1) 
r = radius (m)
ω = angular velocity (rads^-1)

Question 16

If a playground roundabout has many position with different radii do they all have the same angular velocity? what about linear?

Answer 16

yes the angular velocity will stay the same

however people further from the middle will travel faster

Question 17

What is the equation for period?

Answer 17

T = 2(pi) / ω

Question 18

relationship between period and frequency?

Answer 18

f = 1/ω

Question 19

equation for ω using frequency?

Answer 19

ω = 2(pi)ω

Question 20

What is the period?

Answer 20

The time it takes for one revolution

Question 21

What is the frequency?

Answer 21

The amount of complete revolutions in one second