Physics/Maths question

Uraniumfish SG

My physics teacher told us to find out, over the chinese new year period, why 4 is not equal to 4.0 and why 1 1/3 ( one and one third) is not equal to 1.34 . Please explain to me.

tinuviel07 SG

isn't 1 1/3 = 1.333333333333333333333 which is definitely not 1.34

AEW5001 SG

go tell yr teacher at once this:

pls go home n revise yr maths again.

eagle SG

Let me guess... You are in sec 3 this year?

Anyway, this has got to do with significant numbers, under chapter Physical Quantities and Units.

4 means the value can be between 3.5 to 4.499999
4.0 means the value can be between 3.95 to 4.0499999

Garrick_3658 SG

Hey eagle do you want to share something about complex numbers?

StealthLeo SG

Your maths teacher will tell you 4 is always equal to 4.0. As for physics, I still do not have a clue.

eagle SG

Hey eagle do you want to share something about complex numbers?

It's out of O level syllabus. Anyway I have stated the reason why it is different...

A level physics also do not deal with complex numbers. Complex numbers in physics is dealt with at much more advanced levels.... for e.g. simple harmonic motion, where it is used to solve their second order differential equation (along with trigo inside) easier... Then the complex value is ignored.

Also, in electrical engineering, complex numbers are used in circuits, where there are capacitors and inductors, in something called impedance of the circuit. The real value of the impedance is what we will learn as resistance.

All these are already out of A level syllabus, where you only learn complex numbers and argand diagram in H2 Maths... Not much... mildly interesting only...

eagle SG

Your maths teacher will tell you 4 is always equal to 4.0. As for physics, I still do not have a clue.

Physics place a lot of emphasis on accuracy and significant figures. In A level physics, you will also learn to state in terms of uncertainties, i.e. 4 ± 0.1, 4.0 ± 0.02 etc etc

The main difference is that 4 means a larger range of values as compared to 4.0;
or... 4.0 is more accurate than 4.

StealthLeo SG

Physics place a lot of emphasis on accuracy and significant figures. In A level physics, you will also learn to state in terms of uncertainties, i.e. 4 ± 0.1, 4.0 ± 0.02 etc etc

The main difference is that 4 means a larger range of values as compared to 4.0;
or... 4.0 is more accurate than 4.

Understood. My physics has not always been good. Uncertainties and precision have not occured in my mind for this qn.

wee_ws SG

Hi,

In Physics, 4 and 4.0 are not the same. In Maths, an exact value is written as it is, i.e. 4 and not 4.0.

4.0 conveys the idea of an uncertainty of plus or minus 0.1, so the actual value may be between 3.9 and 4.1.

Thanks!

Cheers,
Wen Shih

davidche SG

ah shm, finally i know what this is.

eagle SG

A lvl pple start coming in

Good question by TS!

SBS261P SG

4.0 more accurate than 4?

i thought shld be, 4.0 more precise than 4

Uraniumfish SG

A lvl pple start coming in

Good question by TS!

Thank you. I understand now. Thank you wee_ws.

eagle SG

4.0 more accurate than 4?

i thought shld be, 4.0 more precise than 4

yup.... that's a better term... my bad