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A Level Physics - LVI B > Circular Motion > Flashcards

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.

25

In the rotor/gravitron ride what forces are acting

Vertical equilibrium where weight is balanced by friction
Horizontally its accelerating with normal reaction providing the centripetal force.