Ratios/Proportions in Physics

[msw27]

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Does anyone know any tricks to proportions in the physical sciences section? For instance, those dealing with increasing/decreasing variables in the formulas. I can do most of them but they take me forever, they're just not my cup of tea.🙁

 

[Doc Henry]

I really suck at those too. No real tips for you...except guess, mark it, and move on. Just don't forget to come back to it if you have time.

 

[Vihsadas]

These really take alot of practice. You should practice being comfortable with the common operations and how applying a fraction or whole number factor will affect them. How will sqrt, square, cube, inverse and multiplication of factors will affect the final result?

A big part of getting comfortable with this type of 'proportions' logic is getting comfortable with the terminology. Make sure that if you see something like "X is half as big as Y" that you know exactly what is going up and what is going down.

Practice, practice, practice these problems and try and work through them WITHOUT paper but only for practice. If you get good at working through these problems without paper it will become instinctive how to do these types of problems.

 

[mterp45]

These really take alot of practice. You should practice being comfortable with the common operations and how applying a fraction or whole number factor will affect them. How will sqrt, square, cube, inverse and multiplication of factors will affect the final result?

A big part of getting comfortable with this type of 'proportions' logic is getting comfortable with the terminology. Make sure that if you see something like "X is half as big as Y" that you know exactly what is going up and what is going down.

Practice, practice, practice these problems and try and work through them WITHOUT paper but only for practice. If you get good at working through these problems without paper it will become instinctive how to do these types of problems.

He said exactly what I would have said if I had to advise on this. Nevertheless, I wanted to stress the importance of being able to do these types of problems in your head, it should be second nature, so much that you should consider these types of problems give away points.

 

[SDN2013]

say u have PV=nRT
first recognize that R is a constant, don't worry about it.

Now if a question asks how will increasing the number of moles change pressure,
Move everything to the right so that only P is on the left, so P = nRT/V
and an increase in n would cause an increase in P.

If it was something like F = GMm/r^2
u just gotta remember the r is squared

it's not that hard if you spend some time going over the math to get used to it like others side, and being able to do it in your head will save u time.

 

[LUCPM]

I believe Nova Physics book has an entire chapter dedicated for this proportionality-type problem which is valuable, IMO.

Even if you're not so mathematically inclined, you can become good at this type of problem by practicing and repeating.

Good luck.

 

[wizenedone]

Practice is the key! Make sure you practice, practice and practice. 🙂