9702 · 1.1
Physical quantities — FAQ
Frequently asked questions for 9702 Physical quantities. Direct answers first, then deeper explanation — then practise with marking.
Why are SI units important in physics?
SI units (International System of Units) provide a globally standardised system for measurements, ensuring consistency and clarity in scientific communication and calculations across different countries and disciplines.
Can a vector quantity ever have zero magnitude?
Yes, a vector quantity can have zero magnitude. For example, if an object has zero velocity, its velocity vector has a magnitude of zero. Similarly, if forces are balanced, the resultant force vector is zero.
What's the main difference between an absolute and a percentage uncertainty?
Absolute uncertainty is the raw error value with its units (e.g., ±0.05 m), indicating the range of possible values. Percentage uncertainty expresses this error as a fraction of the measured value (e.g., 2%), useful for comparing precision or combining uncertainties in multiplication/division.