5.2 Circular motion Flashcards

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1
Q

What are radians a unit of?

A

Angle.

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2
Q

How do you convert degrees to radians?

A

To convert an angle from degrees to radians,
divide it by 360 and then multiply by 2π.

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3
Q

What is meant by the period of an object
in circular motion?

A

The time taken for one full rotation.

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4
Q

What is meant by angular velocity?

A

The angle travelled through divided by the
time taken.
This is similar to linear speed, except we’re
interested in rate of rotation rather than
distance/time.

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5
Q

What kind of force is required to keep an
object moving in a circle at constant
speed?

A

A constant centripetal force (a force
applied always towards the centre of that
circle).

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6
Q

True or false: The centripetal force and
velocity of an object moving in a circle
are always in the same direction.

A

False.
Velocity is always at a tangent to the circle,
force is always along a radius. They are
perpendicular.

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7
Q

True or false: The centripetal force and
velocity of an object moving in a circle
are always in the same direction.

A

False.
Velocity is always at a tangent to the circle,
force is always along a radius. They are
perpendicular.

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8
Q

How are linear and angular velocity
related?

A

v = ⍵r

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9
Q

An object moving in a circle at a constant
speed is not accelerating. True or False?

A

False.
The direction is always changing hence
the velocity always changing which
means it is accelerating.

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10
Q

What equation gives acceleration in
terms of angular velocity?

A

a=⍵²r

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11
Q

What is acceleration in terms of linear
velocity?

A

a = v²/r

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12
Q

What are the equations for centripetal
force?

A

F = mv²/r
or
F = m⍵²r

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13
Q

Describe the steps how one can
investigate circular motion via an
experiment

A

● Circular motion can be investigated experimentally by tying a bung, with mass m, to a
piece of string, and threading it through a glass tube.
● The other end of the string has a weight, with mass M, suspended from it. This provides
the centripetal force, F =Mg, as the tension throughout the string is constant.
● The string is whirled in a circle, and the time taken for a complete rotation is recorded.
● The mass of the weight is altered and the experiment repeated.
● We equate Mg and the centripetal force mv²/r so Mg=mv²/r
● By measuring the radius of the circle and using the time for one complete oscillation,
the velocity can be determined. When v^2 is plotted against M, a straight line graph
which passes through the origin should be produced.

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