1.1.A. understand that all physical quantities consist of a numerical magnitude (size) and a unit.
1.1.B. make reasonable estimates of physical quantities included within the syllabus.
A physical quantity consist of a numerical magnitude and a unit.
- All physical quantities can be measured, so that we can compare calculations with experiments or observations. E.g. The height of Mount Everest is 8,848 meters; where 8,848 is the numerical magnitude, and meter is the unit.
- Depends on the circumstances, we may convert units from one system to another: it would be a bit silly (although correct) to say the age of our universe is 436,117,076,640,000,000 seconds. A simple conversion into 13.8 billion years would make our life much easier.
- The length of a pencil can be 100 mm,10 cm, 0.1 m, or 0.0001 km, etc. (which unit is better for a pencil? Why?)
We often express physical quantities in scientific notation. E.g. we write the age of universe as 4.36 x 1017 seconds.
Physics demands a lot of intuition from you. Tips for Physics 👇🏻
- Do sanity check after calculation: it is quite unlikely for a car's speed to be 10000 ms-1.
- Make reasonable estimates: When all fails, never give in! Just make an educational guess .....
- In IGCSE CIE Physics, they may ask you about the speed of sound: A.) 30 ms–1 B.) 300 ms–1 C.) 30000 ms–1 D.) 300000000 ms–1
- 👉 it is unlikely to be 30 ms–1 as it is in the range of animal speed; whereas 300000000 ms–1 probably wrong too, as it is the speed of light. So you are left with B.) and C.) ; An educational guess often (at least) doubles your winning odds!
Richard Woodside, Chris Mee - Cambridge International AS_A Level Physics Revision Education, 2nd Edition
David Sang, Graham Jones, Gurinder Chadha, Richard Woodside - Cambridge International AS and A Level Physics Coursebook, 2nd Edition
That's all, see you next time! 🤘