9702 · 5.2
Gravitational potential energy and kinetic energy flashcards
Revision flashcards for Cambridge 9702 Gravitational potential energy and kinetic energy (syllabus 5.2). Flip, recall, then mark a real past-paper question.
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What is the formula for calculating an object's kinetic energy?
$KE = \frac{1}{2}mv^2$
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How does an object's gravitational potential energy change when its height above a reference point increases?
Its gravitational potential energy increases.
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What three physical quantities are needed to calculate an object's gravitational potential energy near the Earth's surface?
Mass ($m$), acceleration due to gravity ($g$), and vertical height ($h$).
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Describe the energy transformation that occurs as a ball falls from a height, assuming no air resistance.
Gravitational potential energy is converted into kinetic energy, with the total mechanical energy remaining constant.
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Why is the principle of conservation of *mechanical* energy sometimes not observed in real-world situations involving GPE and KE?
Because energy can be lost from the mechanical system due to work done against resistive forces (e.g., air resistance) which converts mechanical energy into other forms, such as heat.
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What does the 'v' stand for in the kinetic energy formula?
'v' represents the object's speed.
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Can gravitational potential energy be negative?
Yes, if the chosen reference point is above the object's position.
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What is 'g' in the GPE formula and what is its approximate value on Earth?
'g' is the acceleration due to gravity, approximately 9.81 m s\textsuperscript{-2} (or 9.8 m s\textsuperscript{-2}).
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What is meant by 'work done' in physics?
Work done is the energy transferred when a force moves an object over a distance in the direction of the force.
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If an object is thrown upwards, what energy transformation occurs as it rises?
Its initial kinetic energy is converted into gravitational potential energy.