Frictional force offers the resistance to the applied force opposing its motion. Thus, it always acts in the direction opposite to that of the object in motion. If force is applied to the left, then friction acts in the right.
        
             
        
        
        
Answer:
a) E₀ = 2.125 eV, b)     # photon2 = 9.2 10¹⁵ photons / mm²
Explanation:
a) To calculate the energy of a photon we use Planck's education
       E = h f
And the ratio of the speed of light
      c = λ f
We replace
       E = h c /λ
Let's calculate
       E₀ = 6.63 10⁻³⁴ 3 10⁸/585 10⁻⁹
       E₀ = 3.40 10⁻¹⁹ J
Let's reduce
      E₀ = 3.4 10⁻¹⁹ J (1 eV / 1.6 10⁻¹⁹ J)
      E₀ = 2.125 eV
b) Let's look for the energy in each pulse
        P = E / t
        E = P t
        E = 20.0 0.45 10⁻³
        E = 9 10⁻³ J
let's use a ratio of proportions (rule of three) if we have the energy of a photon (E₀), to have the energy of 9 10⁻³ J
        # photon = 9 10⁻³ /3.40 10⁻¹⁹
       # photon = 2.65 10¹⁶ photons
Let's calculate the areas
Focus area 
       A₁ = π r²
      A₁ = π (3.4/2)²
      A₁ = 9,079 mm²2
Area requested for calculation r = 1 mm
      A₂ = π 1²
      A₂ = 3.1459 mm²
  
Let's use another rule of three. If we have 2.65 106 photons in an area A1 how many photons in an area A2
     # photon2 = 2.65 10¹⁶ 3.1459 / 9.079
    # photon2 = 9.2 10¹⁵ photons / mm²
 
        
             
        
        
        
Answer:
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Explanation:
Islam ha rideok jja alison onassis William galliano's offensive flagship Isabella r own Christian
 
        
                    
             
        
        
        
Inertia is that quantity which depends solely upon mass. The more mass, the more inertia. Momentum is another quantity in Physics which depends on both mass and speed.
        
             
        
        
        
an atom is chemically stable when its outer layer is completely filled with energy. im pretty sure this is right