9702 · 13.2
Gravitational force between point masses flashcards
Revision flashcards for Cambridge 9702 Gravitational force between point masses (syllabus 13.2). Flip, recall, then mark a real past-paper question.
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What is the fundamental nature of gravitational force?
It is an attractive, non-contact force that exists between any two objects possessing mass.
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What does Newton's Law of Gravitation describe?
The magnitude of the attractive gravitational force between two point masses.
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How does mass affect gravitational force?
The force is directly proportional to the product of the two interacting masses ($m_1 m_2$). This means more mass equals more force.
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How does distance affect gravitational force?
The force is inversely proportional to the square of the distance ($r^2$) separating the centres of the masses.
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State the mathematical formula for Newton's Law of Gravitation.
$F = G \frac{m_1 m_2}{r^2}$
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What does 'G' represent in the gravitational formula?
The universal gravitational constant, a proportionality constant that makes the equation an equality.
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What is the approximate numerical value for G?
\$6.67 \times 10^{-11} \text{ N m}^2 \text{kg}^{-2}$
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What are the units for the universal gravitational constant G?
Newtons metre squared per kilogram squared ($\text{N m}^2 \text{kg}^{-2}$).
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Are gravitational forces ever repulsive?
No, gravitational forces are exclusively attractive; they always pull masses together.
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How is the distance 'r' measured in gravitational calculations?
It must always be measured from the geometric centre of one mass to the geometric centre of the other.
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How can uniform spherical objects be treated as point masses?
For external calculations, their entire mass can be considered concentrated at their geometric centre.
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Why are gravitational forces only significant for large objects like planets?
Because the universal gravitational constant (G) has an extremely small value, making the force negligible for everyday objects.