Solving equations for given variable: S = Vot + 1/2at^2, etc

[yash101]

1.) S = Vot + 1/2at^2 -Solve for a

2.) 1/R = 1/Rsub1 + 1/Rsub2 -Solve for Rsub2

3.) x = 10msub1 + 25msub2 / msub1 + msub2 -Solve for m

4.) T + mg = mv^2 / R - Solve for m

Please if you cannot do all, atleast do one PLEASE. thanks

 

[o_O]

Re: Factoring Alebra mixed!

Why don't you show us your work? Surely you have done some algebra if you're learning physics-related equations ...

 

[yash101]

Re: Factoring Alebra mixed!

truth is I haven't, they just gave me these questions to do by ourselves and we have to write a quiz on it tomorow. so yea please if you can help.

but i started to work on this one.

S = Vot + 1/2at^2

times 2(S) = ( Vot + 1/2 at^2 ) times 2

2S = Vot + at^2

2S / t^2 = Vot + a

I dunno what to do with Vot now. is that right so far??

 

[o_O]

Re: Factoring Alebra mixed!

Seems like you need a bit of a review in algebra. What you're trying to do is isolating the variable to one side using appropriate operations.

S = Vot + 1/2at^2

times 2(S) = ( Vot + 1/2 at^2 ) times 2 Good

2S = Vot + at^2 You forgot to multiply 2 with v[sub:1lwwk0cv]0[/sub:1lwwk0cv]t

2S / t^2 = Vot + a How did you do this? You completely ignored v[sub:1lwwk0cv]0[/sub:1lwwk0cv]t when dividing both sides by t[sup:1lwwk0cv]2[/sup:1lwwk0cv]. You must isolate v[sub:1lwwk0cv]0[/sub:1lwwk0cv]t from the right hand side first before being able to divide both sides by t[sup:1lwwk0cv]2[/sup:1lwwk0cv]

I dunno what to do with Vot now. is that right so far?? If what you did was correct (which it isn't as stated on the previous line), why can't you subtract v[sub:1lwwk0cv]0[/sub:1lwwk0cv]t from both sides?

 

[yash101]

Re: Factoring Alebra mixed!

hmm ok what about this

times 2(S) = (Vot + 1/2at^2) times 2

2S = 2Vot + at^2 (Switch 2Vot to the other side)

2S - 2Vot = at^2

2S -2Vot / t^2 = a

I dunno i am so bad at math

I know i did something wrong in the second step!!

 

[o_O]

Re: Factoring Alebra mixed!

That's perfect!

 

[yash101]

Re: Factoring Alebra mixed!

wow thanks. now for the 2nd one.!!

1/R = 1/Rsub1 + 1/Rsub2

1/R = R[sub:b93k2yqb]1[/sub:b93k2yqb] / R[sub:b93k2yqb]1[/sub:b93k2yqb]R[sub:b93k2yqb]2[/sub:b93k2yqb] + R[sub:b93k2yqb]2[/sub:b93k2yqb]/R[sub:b93k2yqb]1[/sub:b93k2yqb]R[sub:b93k2yqb]2[/sub:b93k2yqb]

!/R = (R[sub:b93k2yqb]1[/sub:b93k2yqb]+R[sub:b93k2yqb]2[/sub:b93k2yqb]) / R[sub:b93k2yqb]1[/sub:b93k2yqb]R[sub:b93k2yqb]2[/sub:b93k2yqb]

R = R[sub:b93k2yqb]1[/sub:b93k2yqb]R[sub:b93k2yqb]2[/sub:b93k2yqb] / R[sub:b93k2yqb]1[/sub:b93k2yqb]+R[sub:b93k2yqb]2[/sub:b93k2yqb]

Although the prob is I only found R, but I need to find R[sub:b93k2yqb]2[/sub:b93k2yqb] How do i find that?

 

[o_O]

Re: Factoring Alebra mixed!

Instead of solving for R first. Why don't you just directly isolate 1/R[sub:6tes2zvz]2[/sub:6tes2zvz]? So:

\(\displaystyle \frac{1}{R} = \frac{1}{R_{1}} + \frac{1}{R_{2}}\)

\(\displaystyle \frac{1}{R} - \frac{1}{R_{1}} = \frac{1}{R_{2}} \quad \mbox{Subtracted } \frac{1}{R_{1}} \mbox{ from both sides}\)

etc. etc.