How fast could the person have to travel?

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Homework Help Overview

The discussion revolves around a relativistic mass increase problem where a person with a mass of 48 kg wishes to gain an additional 12 kg in a different reference frame. Participants are exploring how to calculate the necessary speed to achieve this mass increase using relativistic equations.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants are attempting to clarify the definitions of the variables involved, particularly distinguishing between the rest mass and the relativistic mass. There are questions about the correct use of the relativistic mass equation and how to rearrange it to solve for velocity.

Discussion Status

The discussion is ongoing, with participants providing various interpretations of the mass values and the formula. Some guidance has been offered regarding the rearrangement of the equation to isolate the velocity, but there is still confusion and lack of consensus on the calculations and the correct approach.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may limit the information they can use or the methods they can apply. There is also a noted misunderstanding regarding the speed of light and its representation in calculations.

  • #31
jenita said:
i know this is stupid question...i just came across...do break the square root u have to square it then its (v2/c2) ^2..isnt it

If you have

\sqrt{1 - v^2/c^2}

and square it, you get 1 - v^2/c^2 NOT (1 - v^2/c^2)^2
 
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  • #32
lol...enways is my answer right...can u check it...if it is then thank yooooooouuuuuuuuuuu so much...
 
  • #33
The 2.4 x 10^8 m/s? No, that's not what I get.
 
  • #34
omg this is killing me...let me see what i did wrong
 
  • #35
ok let me check i did 48/60 and i got .8 and squared it after that i squared C and multiplied with .64 and got that answer and i did what u told me to do it...
 
  • #36
\sqrt{1 - v^2/c^2} = \frac{M_o}{M}

See the 1 under the square root on the left side? What happened to that?
 
  • #37
you subtract that and still get the same answer
 
  • #38
hold on a minute let me do it
 
  • #39
i give up...i have 134164078.6 now
 
  • #40
jenita said:
you subtract that and still get the same answer

You do? :confused:

Until you can show me a picture or write out your equation in latex I don't think I am going to be see what you are doing wrong.

I think you are just getting caught up in some small math error.
 
  • #41
v = \sqrt{1-(\frac{M_o}{M})^2} c

This is what you should get after arranging your equation. Please make sure you understand how to get this.

Note: the c is not under the square root.
 
  • #42
let me draw and sent it to you
 
  • #43
hold on how did u get (mo/m) square
 
  • #44
I don't have much time to do it now, it's getting late. If you send it I can try to check it in the morning. :smile:
 
  • #45
jenita said:
hold on how did u get (mo/m) square

Look at post #25. To get rid of the square root, you must square both sides of that equation.

Also see what I said in post #31.
 
  • #46
do u substitute mo/m in v2
 
  • #47
did u get 297993288.5 the answer...if this is wrong i am so giving up
 
  • #48
jenita said:
do u substitute mo/m in v2

NO. Why would you do that?? You want to solve for v. Why would you want to eliminate it from the equation? You are not supposed to be solving for c, if that's what you're up to.

did u get 297993288.5 the answer...if this is wrong i am so giving up
No that's not the right answer.

I gave you the equation for v. Put the numbers in and see what you get. But you must ask for help (perhaps from your teacher) if you can't see how to work out that answer.

Anyway, I must go. Let me know what you come up with and I will check it tomorrow.

Good night.
 
  • #49
good night
and thanks for the help
 
  • #50
I got:

V = Square root (1-(48/60)^2 (c)
=60,000,000

Is that correct?
 
  • #51
i got 1.8*10^8
 
  • #52
Aikenfan said:
I got:

V = Square root (1-(48/60)^2 (c)
=60,000,000

Is that correct?

No, that's not right. You need to both square (Mo/M), and then take the square root of
(1-(Mo/M)^2). It doesn't seem like you did that correctly. At least that's what it looks like to me.
 
  • #53
jenita said:
i got 1.8*10^8

This is the answer I get.
 
  • #54
thanks though...we got the correct answer its .6c ...i know what i did wrong... i already turned in my paper...thanks a looot...u were so helpfull...
 
  • #55
You're welcome. I'm glad you figured out what was going wrong!
 
  • #56
M0 is 48 and M is 60 the speed of light is 3x10 to the power of 8, insert everything in the equation and solve for v and you'll have the answer lol.
 
  • #57
wow...
 
  • #58
jalalmalo said:
M0 is 48 and M is 60 the speed of light is 3x10 to the power of 8, insert everything in the equation and solve for v and you'll have the answer lol.

this thread is over 2 years old...
 
  • #59
:P hehe my bad
 

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