Flashcards in Circular Motion Deck (25)

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1

## Define a radian

### A radian is the angle subtended by a circular arc with a length equal to the radius of the circle.

2

## State the equation to calculate radians

### Radian = arc length/radius

3

## Define time period

###
Time period (T) is the time taken for one complete revolution.

It is measured in seconds (s)

4

## Define frequency

### Frequency is the number of revolutions per second. It is measured in Hertz (Hz)

5

## Define linear velocity

### Rate of change of displacement measured in m/s

6

## Define angular velocity

### Rate of change of angle measured in rad/s

7

## State the relationship between linear velocity and angular velocity

### linear velocity = angolar velocity x radius

8

## State the direction of centripetal force

### Towards the centre of the circle

9

## Define centripetal force

### The overall resultant force acting towards the centre of a circle

10

## State the direction of centripetal force

### Towards the centre of the circle

11

## State the direction of linear velocity

### at a tangent to the circle

12

## What is the angle between centripetal force and linear velocity

### 90

13

## How can an object move at constant speed but still be accelerating?

### if it is moving in a circular path it is constantly changing direction. That must means its velocity is constantly changing. A change in velocity means it is accelerating. it is always accelerating towards the centre of the circle.

14

## State 3 factors that can increase the size of the centripetal force

###
Bigger mass

faster velocity

Smaller radius

15

## Describe a practical to prove the relationship between linear velocity and centripetal force

###
Use a bung attached to some string.

Add masses to the end of the string to vary the centripetal force

Swing the bung in a circular path and time for 10 revolutions.

Calculate the velocity

Keep the mass of the bung and radius of the circle constant. Plot a graph of centripetal force against velocity squared. To prove the relationship the graph should be a straight line that passes through the origin.

16

## What causes the centripetal force for a planetary orbit

### Gravity

17

## What causes the centripetal force for an electron in orbit

### electrostatic attraction

18

## What causes the centripetal force for a bung on a string

### Tension

19

## What causes the centripetal force for a car cornering

### friction

20

## What causes the centripetal force for a car cornering on a banked slope.

### Normal reaction resolved horizontally and friction resolved horizontally

21

## What causes the centripetal force for an airplane banking

### upthrust resolved horizontally

22

## What causes the centripetal force for a rollercoaster at the top of a loop the loop

### Reaction + weight

23

## What causes the centripetal force for a rollercoaster at the bottom of a loop the loop

### Reaction - weight

24

## Why is the normal reaction for a rollercoaster greater at the bottom of a loop the loop that at the top

###
At the top the weigh helps contribute to the centripetal force.

At the bottom the reaction force has to overcome all the weight and then provide the centripetal force.

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