The environmental protection agency (EPA) has proposed a new standard for microparticulates in air: For particles up to 2.5 um in diameter, the maximum allowable amount is 50 ug/m3. If your 9.2 ft x 13.8 ft x 8.6 ft dorm room just meets the new EPA standard, how many of these particles are in your room? (Assume the particles are spheres of 2.5 um diameter, and made primarily of soot, a form of carbon with a density of 2.5 g/cm3.)

In the diffraction experiment shown in the figure, the source emits particles of momentum P0, mass M and velocity v.
What is the spacing "a" between the central maximum and the neighboring maxima? Assume L>>d, L>>a.
Diagram attached.

The positions of two particles on the s-axis are s1=sin t and s2=sin(t+ π /3), with s1 and s2 in meters and t in seconds.
a) At what time(s) in the interval 0 ≤t ≤ 2π do the particles meet?
b) What is the farthest apart that the particles ever get?
c) When in the interval 0 ≤t ≤ 2π is the distance between the parti

The environmental protection agency (EPA) has proposed a new standard for microparticulates in air: For particles up to 2.5 um in diameter, the maximum allowable amount is 50 ug/m3.
a) If your 9.2 ft x 13.8 ft x 8.6 ft dorm room just meets the new EPA standard, how many of these particles are in your room? (Assume the particle

From its atomic weight (239) and its half-life (24000 years) calculate how many alpha particles are emitted by 3.5 micrograms of plutonium over the course of a year.
I'm not sure how to calculate the number of alpha particles with the given information.

Consider a lattice of N particles in an external homogeneous magnetic field,
where each particle has two possible energy states, depending on whether the spin of the particle points in the direction of the magnetic field ("down") or opposite to it ("up"). In the "down" state the particle has no energy e = 0 and in the "up" s

The magnitude (size) of the force,
, between two charged particles a distance
apart is given by the equation below. Ke is a constant.
Rearrange this equation to make Ke the subject.
F = Ke Q1 Q2
r2
The answer should not include any brackets and should use super/sub script w

Positronium is an atom composed of an electron and a positron (mp = me, Q = +e). Calculate the distance between the particles and the energy of the lowest energy state of positronium. Hint: the reduced mass µ of the two particles equals me/(1 + me/m).
-----------------a0
------------------E0

A beam of 6 MeV particles scatters from a gold foil of thickness of 0.6 µm.
(a) What fraction of the particles is scattered between 1° and 2°?
(b) What is the ratio of particles scattered through angles greater than 2° to the number scattered through angles greater than 15°?
What is the ratio of particles scattered thr

1) As the distance between two oppositely charged particles is tripled, _____.
a. the attractive force is one-third as large
b. the attractive force increases by a factor of three
c. the attractive force is one-ninth as large
d. the repulsive force is one-ninth as large