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/sci/ - Science & Math

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7613284 No.7613284 [Reply] [Original]

Cam across this weird problem while reading ahead in my physics book
Am I missing something here?

Also Coefficient of friction (uk)= about 0.048

>> No.7613287

>>7613284
came*

>> No.7613304

>>7613284
To be clear the fist equation (One with m) gets the answer correct while the second equation gets the wrong answer with makes no sense because the "m" cancels out.

>> No.7613341
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7613341

>>7613287
>came*

>> No.7613402

>>7613284
Why are you figuring out the coefficient of friction, you are making extra work for yourself. They give you the final force it generates, which is -950 if you say the other force is in the positive direction. so the final equation is mv^2/(1140-950) = d.

But more specifically for your question. You can't remove something for the denominator if it isn't outside of the brackets of the addition or subtraction part. If that explanation doesn't make sense I can post a picture explaining it better.

>> No.7613418
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7613418

>>7613402
This is basic algebra

>> No.7613427

>>7613402
Ohh I see it's because of the parenthesis. I would need to solve that before canceling anything out huh? Kinda figured that out a bit later. I guess I just need to brush up on math and start sleeping on time lol

>> No.7613437

>>7613427
No its not because of the parenthesis, x/(x-1) isn't 1/-1 Which is what you are saying it is equal to by cancelling out the masses. x/(xyz) = 1/yz is a situation where you can cancel things off because there is one term in the denominator and numerator.

Is this a high school physics course?

>> No.7613468

>>7613437
So theoretically if it was mv^2/fm-blahblah I would have been able to cancel it out? I get it now thank you man.
I guess this is what happens when you don't pay attention in math class for like 4years (sigh)

Yup, But this is actually like 3 Chapters ahead from the class, they are still on free-body diagrams atm.

>> No.7613482

>>7613468
yea if the blahblah had an m in it somewhere. Because then you could take the m out and say you're multiplying it by both terms, which would look like [eqn]mv^2/m(F-blahblah)[/eqn] so you could cancel it.

Don't waste your time writing so much non-sense out when solving physics equations. You should expect the person reading it to have basic knowledge of physics so they can understand. Unless your teacher told you to.

>> No.7613501

>>7613482
I know I actually messed up at first, went to much into it then realized later on I didn't need to do any of the extra step. But I messed up basic algebra and decided to write it all out to figure out where I wen't wrong.
Your right tho. I actually think I might re-take some math courses to actually learn shit don't wanna fuck up this bad anymore lol.