## When to multiply by 2

$\Delta p \Delta x\geq \frac{h}{4\pi }$

Jessica Dharmawan 1G
Posts: 32
Joined: Fri Sep 28, 2018 12:15 am

### When to multiply by 2

When do we multiply the uncertainty in p or x or v by 2? I'm getting confused when doing calculations.

Kathryn 1F
Posts: 66
Joined: Fri Sep 28, 2018 12:19 am

### Re: When to multiply by 2

Do you mean like if the value is given like "the velocity is 10 +- 1 m/s"? in this case, the indeterminacy in velocity is 2, as the velocity could be between 9 and 11. So you would take the +-1 * 2.

If it says "the indeterminacy is (delta)2", then you can take that as is

Sydney Aurelio_Dis4B
Posts: 30
Joined: Fri Sep 28, 2018 12:28 am

### Re: When to multiply by 2

If you are referring to a question like on test 2 #2. You multiply momentum by a certain factor, ex) 2. when the problem says "The uncertainty in the momentum of a ball is 2 times its momentum" In that sort of example you would calculate the momentum, then multiply that value by 2 to get the uncertainty in momentum

ariana_apopei1K
Posts: 89
Joined: Fri Sep 28, 2018 12:27 am
Been upvoted: 1 time

### Re: When to multiply by 2

You would multiply by 2 when you're given something like +/-0.5 as your value. This uses the same reasoning as the first answer on this post, the two outermost values we can get are .5 and -.5, so when you subtract them (.5--.5) you get 1, the same thing as multiplying .5 times 2.

Ana Pedreros
Posts: 62
Joined: Fri Sep 28, 2018 12:19 am

### Re: When to multiply by 2

Would we still multiply it by 2 if we are just given the velocity like 10 m/s?

Sophia Ding 1B
Posts: 62
Joined: Fri Sep 28, 2018 12:16 am

### Re: When to multiply by 2

No, if you're just given the velocity you would use that value given. You'd only multiply by 2 if given a range as stated before, like a velocity +/- .35 (for example), as that the .35 dictates the uncertainty and must multiply by 2 to account for the +/- range of it.