Water may come into contact with very hot rock heated by magma
Answer:
a) P=0.25x10^-7
b) R=B*N2*E
c) N=1.33x10^9 photons
Explanation:
a) the spontaneous emission rate is equal to:
1/tsp=1/3 ms
the stimulated emission rate is equal to:
pst=(N*C*o(v))/V
where
o(v)=((λ^2*A)/(8*π*u^2))g(v)
g(v)=2/(π*deltav)
o(v)=(λ^2)/(4*π*tp*deltav)
Replacing values:
o(v)=0.7^2/(4*π*3*50)=8.3x10^-19 cm^2
the probability is equal to:
P=(1000*3x10^10*8.3x10^-19)/(100)=0.25x10^-7
b) the rate of decay is equal to:
R=B*N2*E, where B is the Einstein´s coefficient and E is the energy system
c) the number of photons is equal to:
N=(1/tsp)*(V/C*o)
Replacing:
N=100/(3*3x10^10*8.3x10^-19)
N=1.33x10^9 photons
Answer :
(a) The initial velocity is, 14.8 m/s
(b) The acceleration is, 
Explanation :
By the 1st equation of motion,
...........(1)
where,
v = final velocity = 0 s
u = initial velocity
t = time = 6.35 s
a = acceleration
The equation 1 will be:

..........(2)
By the 2nd equation of motion,
...........(3)
where,
s = distance = 47 m
Now substitute equation 2 in 3, we get:

By solving the term, we get:

The acceleration is, 
Now we have to calculate the initial velocity.
Using equation 2, we gte:



The initial velocity is, 14.8 m/s
Answer:
B. Arsenic
Explanation:
76 - 43 = 33 protons
on a periodic table element 33 is Arsenic
By using Ohm's law, we can calculate the resistance of the wire. Ohm's law states that:

where V is the potential difference across the conductor, I is the current and R the resistance. Rearranging the equation, we get

Now we can use the following equation to calculate the length of the wire:

(1)
where

is the resistivity of the material
L is the length of the conductor
A is its cross-sectional area
In this problem, we have a wire of copper, with resistivity

. The radius of the wire is half the diameter:

And the cross-sectional area is

So now we can rearrange eq.(1) to calculate the length of the wire: