Units (Forces and Motion)
2 marks · HardA physics textbook lists a unit as "newton per kilogram". Describe a physical situation where this unit might be used, and write down its symbol. Do not use gravitational field strength as your answer.
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It could be used to describe the spring constant per unit mass, symbol N/kg. Example: measuring elasticity where force per kilogram of material is considered.
Must show: newton per kilogram situation (not g), unit symbol N/kg
Also accept: describing force per kg for a resistant material; explaining N/kg in Hooke’s law context
Common mistakes: incorrectly defining it as unit for acceleration; using only gravitational field strength example
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Marking points
B1 · 1 mark · Correct use of unit in a context other than gravitational field strength.
B2 · 1 mark · Correct symbol N/kg given.
Worked solution
A possible situation is a spring system designed so that for every kilogram of load, a force of 20 N is applied (e.g., industrial weighing machines use calibration in N/kg for material loading). Symbol is N/kg.