# Help Uncertainity principle problem

1. Nov 27, 2007

### indiepunkband

in my problem i am told
that the x-component of the velocity of a 2x10^-4 kg mass is measured to an accuracy of +_ 10^-6 m/s.
i need to find the limit of the accuracy with which the particle can be located along the x-axis.

the uncertainity principle
delta(x) * delta(Px)>= h/4pi
i have delta(Vx) and i need delta(x)

2. Nov 27, 2007

### malawi_glenn

this is not homework sub-forum, here we post general questions about QM.

someone will move this thread to the right sub-forum, just so know in the future.

Also you need to show some work before you get help.

but I can give you a hint: calculate the deltaP, you have mass and deltaV, it is straightforward.

3. Sep 27, 2009

### iwant2know

If black holes are described as having no volume of space, yet they are 'mass" via density.
Mass density= MASS per VOLUME of SPACE.
So, density = mass per volume, & in order to MEASURE the density of something is to measure its MASS, then measure its VOLUME then divide MASS/VOLUME.

Why does there seem to be a contradiction?