16 - Circular Motion Flashcards

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1
Q

Define the radian.

A

The angle subtended by a circular arc with a length equal to the radius of the circle.

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2
Q

What is 360° in radians?

A

360° = 2π radians

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3
Q

How do you convert between radians and degrees?

A

Divide the angle by π.

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4
Q

What is angular velocity of an object in circular motion?

A

The rate of change of angle.

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5
Q

What is the frequency of an object in circular motion?

A

The number of rotations per unit time. (Hz)

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6
Q

What is the frequency of an object in circular motion?

A

The time taken to complete one rotation. (Seconds)

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7
Q

What are the two equations for angular frequency?

A

ω = 2πf

ω = 2π / T

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8
Q

What is the symbol for angular frequency

A

ω

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9
Q

What is the most commonly used unit for angular frequency?

A

rad s⁻¹

Radians per second

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10
Q

What does any object require in order to accelerate?

A

A resultant force to be acting on it.

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11
Q

What is centripetal force?

A

Any force that keeps a body moving with a uniform speed along a circular path.

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12
Q

In what direction does a centripetal force always act?

A

Perpendicular to the velocity of the object.

Towards the centre of the circle.

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13
Q

What would the centripetal force be in the following situations?

  • Car going round a bend
  • Satellite in orbit
  • Yo-yo swung on a string
A
  • Friction
  • Gravity
  • Tension
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14
Q

How do we calculate the velocity of an object in circular motion?

A

v = ωr

Speed = Distance / Time

One rotation: Distance = 2πr (Circumference)
Time = T (Period)

                   2πr / T --> ωr    (ω = 2π / T)
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15
Q

What is the linear velocity at any instance proportional to?

A

v ∝ r

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16
Q

What is centripetal acceleration?

A

The acceleration of any object travelling in circular motion at a constant speed.

17
Q

What direction does centripetal acceleration always act?

A

Perpendicular to velocity.

Towards the centre of the circle.

18
Q

What are the two equations for centripetal acceleration?

A

a = v² / r

a = ω²r

19
Q

What equation for force do we combine with an equation for centripetal acceleration to get centripetal force?

A

F = ma

20
Q

What are the two equations for centripetal force?

A

F = mv² / r

F = mω²r

21
Q

What happens if the centripetal force is not great enough?

A

The object does not follow circular motion and the radius of the circle will increase.

22
Q

How do banked surfaces increase the velocity that vehicles can go round corners at?

A

It means that it is not just friction but a horizontal component of the normal contact force that provides centripetal force, meaning this is greater.