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Which two quantities have the base unit kg m² s⁻²? A kinetic energy and momentum B kinetic energy and Young modulus C work done and the moment of a couple D work done and pressure - AQA - A-Level Physics - Question 7 - 2022 - Paper 1
Question 7
Which two quantities have the base unit kg m² s⁻²? A kinetic energy and momentum B kinetic energy and Young modulus C work done and the moment of a couple D work... show full transcript
Worked Solution & Example Answer:Which two quantities have the base unit kg m² s⁻²? A kinetic energy and momentum B kinetic energy and Young modulus C work done and the moment of a couple D work done and pressure - AQA - A-Level Physics - Question 7 - 2022 - Paper 1
Step 1
C work done and the moment of a couple
Answer
To determine which quantities have the base unit kg m² s⁻², we analyze the units of each option:
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Kinetic Energy (KE) is defined as: The unit is Joules (J), which can be expressed in base units as kg m² s⁻².
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Momentum (p) is defined as: The unit is kg m/s.
This means that option A does not consist of two quantities that share the same unit.
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Young Modulus has units of pressure (force per area), which is N/m² or kg m⁻¹ s⁻², hence option B is also excluded.
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Work Done (W) is given by: The unit is also Joules (kg m² s⁻²), which corroborates the first part of option C.
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The Moment of a Couple has units of N·m (Newton meters), which is equivalent to kg m² s⁻².
Thus, option C is correct as both 'work done' and 'the moment of a couple' share the base unit kg m² s⁻².