KE of a dust particle?

[user101]

1. The problem statement, all variables and given/known data

Find the KE of a dust particle that weighs 1 micrograms traveling at a speed of 1 mm/s

2. Relevant equations

E = \frac{mv^2}{2}

3. The attempt at a solution

Would this question be applicable to the equation listed above? I thought it was only applicable to electrons in orbit, around a nucleus. I'm questioning this because it's a dust particle...

[cristo]

The formula you give holds for any particle moving at speeds not close to the speed of light so, yes, it would be the one to use here.

[Astronuc]

The definition of kinetic energy for a given mass m at a speed (magnitude of velocity) v, is given by the equation cited, from electrons to galaxies - but at non-relativistic speeds.

For a collection of particles v would be the mean translational speed, and then there could be rotational kinetic energy.

See - http://hyperphysics.phy-astr.gsu.edu/hbase/ke.html#ke

[user101]

Thank you, makes sense now.

Quick question:

If I'm multiplying grams * meters / second... what unit is that? I've been trying to figure that out, can't do it... Ideally I'd like my answer to be in Joules

* I just realized, this should be in the introductory physics section, sorry. I had posted a Q yesterday in this forum for an upper level physics class, so I programmed myself to post this simple Q here.

[Astronuc]

1 J = 1 kg * (1 m/s)2 = 1 Nt * 1 m.

These are SI or MKS units.


See - http://hyperphysics.phy-astr.gsu.edu/hbase/units.html#uni4

or http://hyperphysics.phy-astr.gsu.edu/hbase/units.html

or http://physics.nist.gov/cuu/Units/units.html