## Sample Problem (Example 1.7// Textbook)

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

Frenz Cabison 1B
Posts: 54
Joined: Fri Sep 29, 2017 7:07 am

### Sample Problem (Example 1.7// Textbook)

Hi! So I was looking at the sample problem from the book and the problem is: Estimate the minimum uncertainty in the position of a marble mass 1.0 g given that its speed is known to within plus/minus 1.0 mms^-1.

On the "solve" part of the problem, it says to first convert mass and speed into SI base units. It sas that the mass, m, is 1.0x10^-3 kg, and the uncertainty in the speed, delta v, is 2 x (1.0x10^-3ms^-1).

My question is where did the "2" come from? Do we always have to multiply the uncertainty in the speed by two?

Jessica Jones 2B
Posts: 80
Joined: Fri Sep 29, 2017 7:04 am

### Re: Sample Problem (Example 1.7// Textbook)

The 2 come from doubling the uncertainty because it is +/- 1x10^-3. This means that you must add the uncertainty +1.0x10^-3 and -1.0x10^-3(but make this positive for the addition)

MichelleKaku1H
Posts: 21
Joined: Fri Sep 29, 2017 7:04 am

### Re: Sample Problem (Example 1.7// Textbook)

Yes! Even though you weren't specifically given a velocity, you can find the delta v by multiplying the uncertainty in velocity by two to account for adding and subtracting 1.00x10^-3 m/s.