The energy carried by the incident light is
where h is the Planck constant and f is the frequency of the light. The threshold frequency is the frequency that corresponds to the minimum energy needed to eject the electrons from the metal, so if we substitute the threshold frequency in the formula, we get the minimum energy the light must have to eject the electrons:
Before the engines fail 
, the rocket's horizontal and vertical position in the air are
and its velocity vector has components
After 
, its position is
and the rocket's velocity vector has horizontal and vertical components
After the engine failure 
, the rocket is in freefall and its position is given by
and its velocity vector's components are
where we take 
.
a. The maximum altitude occurs at the point during which 
:
At this point, the rocket has an altitude of
b. The rocket will eventually fall to the ground at some point after its engines fail. We solve 
for 
, then add 3 seconds to this time:
So the rocket stays in the air for a total of 
.
c. After the engine failure, the rocket traveled for about 34.6 seconds, so we evalute 
for this time :
<span>E=hc/wav. len
E = (6.62 x 10^-34 x 3 x 10^8)/0.0275 x 10^-9
E = 7.22182 x 10^-15 J
To convert to eV divide by 1.6 x 10^-19
E = 7.22182 x 10^-15/1.6 x 10^-19 eV
E =45.36 x 10^3 eV
Th energy, E, of a single x-ray photon in eV is = 45.36keV.
Number of photons, n = total energy/ energy of photon
n = 3.85 x 10^-6/7.22182 x 10^-15
n = 5.33 x 10^8 photons </span>
B would be an example of vaporization (liquid to gas).
———————
A is an example of deposition (gas to solid); C is an example of condensation (gas to liquid); and D is an example of condensation, deposition, or freezing—depending on the type of cloud.
