Question 7
MediumOriginal questionWhich of the following is a base quantity in the SI system?
Show the answer and explanation
CorrectNot quiteAnswer C
Correct answer: C
Explanation
The SI system defines seven base quantities: length, mass, time, electric current, thermodynamic temperature, amount of substance and luminous intensity.
Luminous intensity is on that list, measured in candela.
Force, velocity and pressure are all derived: velocity is length over time, force is mass times acceleration, and pressure is force over area.
Worth noting
A quick test for a derived quantity is whether you can write its unit in terms of others — newtons, metres per second and pascals all decompose, candela does not.
- Concept
- Base and derived quantities
- Typical timeTypical
- 50 s
- Your timeYours
- —
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