Physics Question

[Limesparks]

i use different sized letters and pyramid thingies and triangle dots im sooo special

[madnak]

That's an interesting derivation, I especially like the second line (I didn't notice that). But I don't understand how this is easier, or how we're "leaping off a bridge." I thought we were solving them algebraically. I suspect that your familiarity with math and symbols makes this more intuitive to you.

[gumpzilla]

[ QUOTE ]
That's an interesting derivation, I especially like the second line (I didn't notice that). But I don't understand how this is easier, or how we're "leaping off a bridge." I thought we were solving them algebraically. I suspect that your familiarity with math and symbols makes this more intuitive to you.

[/ QUOTE ]

If you make a mistake with numbers already plugged in, good luck finding out what the error was. If you make the mistake with abstract symbols plugged in, it can be very easy to identify. (EDIT: It also allows you to make common sense checks. A distance should be a speed times a time; do we end up with that? If the speed difference between air and concrete is very small, then a small time difference should correspond to a big distance difference; is this true? Etc.)

[madnak]

But I used symbols! I don't see how the subscripts or the deltas are necessary. All three of us wrote out the constants in explaining the basic problem, but we didn't mash them together or anything. I agree that it's problematic to merge two terms together using arithmetic (and then lose them), it's better to use symbols, but that's why I use a, b, and c when I do the algebra portion. And yes, units matter, but not so much in this case.

I really don't see a difference between using a, b, c and using vsubc, vsuba, deltat. Also just saying (t2-t1) instead of delta t, or saying so/therefore instead of (three dots) is clearer for those who don't know what the symbols mean.

[Borodog]

[ QUOTE ]
That's an interesting derivation, I especially like the second line (I didn't notice that). But I don't understand how this is easier, or how we're "leaping off a bridge." I thought we were solving them algebraically. I suspect that your familiarity with math and symbols makes this more intuitive to you.

[/ QUOTE ]

What gumpzilla said about plugging in numbers. Make one small mistake and good luck finding it. Make a mistake in your symbolic algebra, and it is easy to find.

Also, his point about dimensions is really critically important every post in this thread had a bunch of dimensionless numbers in it (3000, 343, 0.75). This is *wrong*. All of the expressions written were dimensionally incorrect. By throwing out the units you throw out critical information that can allow you to catch and correct errors.

What if I had forgotten to multiply my answer by the speed of sound in concrete in the last step? I wouldn't even have something that had dimensions of distance; it would be a time instead:



It couldn't possibly be correct. If I don't keep track of my units, I have no way of catching such a mistake.

[Borodog]

[ QUOTE ]
I really don't see a difference between using a, b, c and using vsubc, vsuba, deltat. Also just saying (t2-t1) instead of delta t

[/ QUOTE ]

Why do we call a steering wheel a steering wheel and not a krabbanufratz? [img]/images/graemlins/wink.gif[/img]

[mikeczyz]

[ QUOTE ]
You guys are killing me.



Edit: Let me know if I have to explain that.


[/ QUOTE ]
christ. I wish my physics prof had taught this to us.

[madnak]

I was going to argue, but then I realized all the ways that using proper notation can be helpful. I see your point.

[kerowo]

Sorry I didn't keep all the units there, there weren't that many and it was mostly an excercise to see if I remembered how to do that stuff. Boro is right, if you knew how to do that derivation it would be easier.

[goofball]

Letters > numbers is by far the most important thing anyone should take away from this thread.