## shortcake1970 Group Title if you were to travel to a star 50 light years from earth at a speed of 2.0 X 10 to 8th power m/s, what would you measure this distance to be? one year ago one year ago

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1. calculusfunctions Group Title

@shortcake1970 do you know the definition of a light year?

2. calculusfunctions Group Title

A light year is the distance that light travels in one Earth year.

3. VeritasVosLiberabit Group Title

light travels at 3*10^8 m/s

4. calculusfunctions Group Title

Yes that's approximately the speed of light, as @VeritasVosLiberabit said.

5. VeritasVosLiberabit Group Title

so it seems the 2*10^8 is meant to throw you off because it is irrelevant to finding the distance

6. shortcake1970 Group Title

and the distance light travels in a year is 9.47 X 10^15 i have that much

7. calculusfunctions Group Title

Now find the number of seconds in one Earth year. Yes @VeritasVosLiberabit , that is extraneous information. Not needed.

8. VeritasVosLiberabit Group Title

it might be better to keep your calculations in MKS units unless told otherwise.

9. calculusfunctions Group Title

Alright @shortcake1970 now simply multiply that answer by 50.

10. shortcake1970 Group Title

so do I just multiply?

11. calculusfunctions Group Title

Haha that's what I said.

12. shortcake1970 Group Title

oops yup you just answered that

13. shortcake1970 Group Title

Thank you!

14. calculusfunctions Group Title

Welcome!

15. calculusfunctions Group Title

Need help with anything else or are you okay?

16. shortcake1970 Group Title

well I do have another questions I might need help with let me write it...

17. calculusfunctions Group Title

Sure

18. calculusfunctions Group Title

Are these questions you've tried yourself? It's important you try them yourself first.

19. shortcake1970 Group Title

a beam of a certain type of elementary particle travels at a speed of 2.8 X 10^8 m/s. at this speed the average lifetime is measured to be 2.5 X 10^-8 s. what is the particle's lifetime at rest. let me tell you what formula i was thinking of using

20. shortcake1970 Group Title

once i know which formula i can work it out myself :)

21. calculusfunctions Group Title

Sorry I was away for a minute. Just give me second. I'm just in the middle of something.

22. shortcake1970 Group Title

ok i'm having a hard time typing the formula

23. shortcake1970 Group Title

delta t=delta t o /square root of 1-v^2/c^2

24. calculusfunctions Group Title

OK I'm back. Yes$\Delta t =\frac{ \Delta t _{0} }{ \sqrt{1-\frac{ v ^{2} }{ c ^{2} }} }$

25. calculusfunctions Group Title

Do you understand? $\Delta t = 2.5\times10^{-8}s$$v =2.8\times10^{8}m/s$$c =3.0\times10^{8}m/s$$\Delta t _{0}=?$Rearrange the formula first to get$\Delta t _{0}=\Delta t \sqrt{1-\frac{ v ^{2} }{ c ^{2} }}$

26. shortcake1970 Group Title

.90 x 10^8 s

27. calculusfunctions Group Title

Give me a second to calculate it.

28. shortcake1970 Group Title

is the answer for the previous question 4.73 x 10^17?

29. calculusfunctions Group Title

It should be$9.0\times10^{-9}$

30. calculusfunctions Group Title

That exponent is negative 9

31. shortcake1970 Group Title

oh i see

32. calculusfunctions Group Title

Do you? Did you spot your error?

33. shortcake1970 Group Title

yes i spotted the error

34. calculusfunctions Group Title

Great. I have to go but is there anything else before I do?

35. calculusfunctions Group Title

I guess not. I might be back a little later. Bye.

36. shortcake1970 Group Title

thank you so much.