Circular Motion Flashcards

To revise the circular motion topic

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1
Q

Define a radian

A

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

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2
Q

State the equation to calculate radians

A

Radian = arc length/radius

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3
Q

Define time period

A
Time period (T) is the time taken for one complete revolution.
It is measured in seconds (s)
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4
Q

Define frequency

A

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

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5
Q

Define linear velocity

A

Rate of change of displacement measured in m/s

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6
Q

Define angular velocity

A

Rate of change of angle measured in rad/s

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7
Q

State the relationship between linear velocity and angular velocity

A

linear velocity = angolar velocity x radius

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8
Q

State the direction of centripetal force

A

Towards the centre of the circle

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9
Q

Define centripetal force

A

The overall resultant force acting towards the centre of a circle

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10
Q

State the direction of centripetal force

A

Towards the centre of the circle

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11
Q

State the direction of linear velocity

A

at a tangent to the circle

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12
Q

What is the angle between centripetal force and linear velocity

A

90

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13
Q

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

A

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.

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14
Q

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

A

Bigger mass
faster velocity
Smaller radius

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15
Q

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

A

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.

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16
Q

What causes the centripetal force for a planetary orbit

A

Gravity

17
Q

What causes the centripetal force for an electron in orbit

A

electrostatic attraction

18
Q

What causes the centripetal force for a bung on a string

A

Tension

19
Q

What causes the centripetal force for a car cornering

A

friction

20
Q

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

A

Normal reaction resolved horizontally and friction resolved horizontally

21
Q

What causes the centripetal force for an airplane banking

A

upthrust resolved horizontally

22
Q

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

A

Reaction + weight

23
Q

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

A

Reaction - weight

24
Q

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

A

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
Q

In the rotor/gravitron ride what forces are acting

A

Vertical equilibrium where weight is balanced by friction

Horizontally its accelerating with normal reaction providing the centripetal force.