9702 · 12.1
Kinematics of uniform circular motion flashcards
Revision flashcards for Cambridge 9702 Kinematics of uniform circular motion (syllabus 12.1). Flip, recall, then mark a real past-paper question.
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Define uniform circular motion.
Movement in a circular path at a constant speed, but with continuously changing velocity due to direction change.
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What is angular displacement and its standard unit?
The angle swept out by an object from the center of its circular path, measured in radians (rad).
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How many radians are equivalent to one complete revolution?
$2\pi$ radians ($360^\circ$).
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How are period ($T$) and frequency ($f$) related?
Frequency is the reciprocal of the period: $f = \frac{1}{T}$.
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Define angular velocity ($\omega$) and state its SI unit.
The rate of change of angular displacement. Its SI unit is radians per second (rad s⁻¹).
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State the relationship between linear speed ($v$), angular velocity ($\omega$), and radius ($r$).
$v = \omega r$.
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Explain why an object moving at a constant speed in a circle is still accelerating.
Its velocity direction is continuously changing, and since velocity is a vector, a change in direction means a change in velocity, thus an acceleration.
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What is the direction of centripetal acceleration?
Always towards the center of the circular path.
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Provide two formulas for calculating centripetal acceleration ($a_c$).
$a_c = \frac{v^2}{r}$ or $a_c = \omega^2 r$.
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What is centripetal force and its direction?
The resultant force required to keep an object moving in a circular path, always directed towards the center of the circle.
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State two formulas for centripetal force ($F_c$).
$F_c = \frac{mv^2}{r}$ or $F_c = m\omega^2 r$.
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What is the relationship between angular velocity ($\omega$), period ($T$), and frequency ($f$)?
$\omega = \frac{2\pi}{T}$ and $\omega = 2\pi f$.
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Is centripetal force a fundamental force of nature?
No. It is the resultant force directed towards the center of the circle, provided by other forces like gravity, tension, or friction.
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What force provides the centripetal force for a car turning on a flat road?
The static frictional force between the tires and the road surface.
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What force provides the centripetal force for a satellite in a stable orbit around a planet?
The gravitational force of attraction between the satellite and the planet.