You need to find the mass of water in the pool.
Find the volume (10 x 4 x 3) = 120 m3
Water has a density of 1000g/m3,so 120 m3 = 120 x 1000 = 120 000 kg
[delta]H = 4.187 x 120 000 x 3.4 (and the units will be kJ)
You then use the heat of combustion knowing that each mole of methane
releases 891 kJ of heat so if you divide 891 into the previous answer,
you will get the number of moles of CH4
230 Newton
Electric charge consists of two types i.e. positively electric charge and negatively electric charge.There was a famous scientist who investigated about this charges. His name is Coulomb and succeeded in formulating the force of attraction or repulsion between two charges i.e. :
F = electric force (N)
k = electric constant (N m² / C²)
q = electric charge (C)
r = distance between charges (m)
The value of k in a vacuum = 9 x 10⁹ (N m² / C²)
F = k(q1 q2)/ r^2
Distance between protons = d = 10⁻¹⁵ m
charge of proton = q = 1.6 × 10⁻¹⁹ C
Here q1=q2
electric force = F =230N
Coulomb's Law. Two protons in an atomic nucleus are typically separated by a distance of 2×10−15m. The electric repulsive force between the protons is huge, but the attractive nuclear force is even stronger and keeps the nucleus from bursting apart.
2 Nuclei and the Need for an Attractive Nuclear Force. The Coulomb force also acts within atomic nucleii, whose characteristic dimension is 10 m, which is called a fermi. There are two protons in a He nucleus, which repel each other because of the Coulomb force.
Find more about electric force of repulsion between nuclear protons
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Answer:

Explanation:
Given that,
The wavelength of light, 
We need to find the frequency of the light. We know that,

So, the required frequency of light is equal to
.
Answer:
7327 kg or 7.3 tons
Explanation:
We have Newton formula for attraction force between 2 objects with mass and a distance between them:

where
is the gravitational constant on Earth.
is the masses of the 2 objects. and R = 2.6m is the distance between them.
is the attraction force.



or 7.3 tons
I think it might be a gravitational pull