Available options are:
A. –4500 N
B. –2500 N 
C. 2500 N 
D. 4500 N
Answer:
-4500 N
Explanation:
Given that we have F₁ = 3000N? (force of the barge)
 the force of the tugboat is F ' 
To pull the barge, the force of the tugboat must be greater than or equal to the force of the barge.
Hence, according to Newton's third law which states that for every action or force in nature, there is an opposite reaction.
Therefore considering the available option the correct answer is "- 4500N, " this is because it is greater than the force of the barge and it's in opposition to the force exerted.
 
        
                    
             
        
        
        
<h2>Answer: The <u>height</u> of a sound wave determines its <u>loudness</u>  </h2>
Sound waves are longitudinal mechanical waves, that is, they depend on a medium to propagate.
Among the characteristics of a sound wave, it is the amplitude, that is the degree of movement of the molecules of the medium in which the wave propagates.  
Depending on how high this amplitude is, the sound will be louder.
 
        
        
        
Answer:

Explanation:
Under this  condition, . In order to suspend the wire, this magnetic force would  have to be equal in magnitude to the gravitational force exerted by Earth on the  wire the maximum force at angle 
F=ILxB
Now to the suspend the wire so use the maximum force and solve to the current knowing the magnetic field of the earth 
∑Fy=0


Solve to I current 



I suggest do an toher act is really risk that current for an act 
 
        
             
        
        
        
Answer: This is called the Doppler effect, where waves shift frequency and wavelength as the source travels towards you (higher frequency, shorter wavelength) or away from you (lower frequency, longer wavelength)
Explanation:
hoped this helped have a good day :)
 
        
             
        
        
        
Answer:
a) True. The number of photoelectrons is proportional to the amount (intensity) of the incident beam. From the expression above we see that threshold frequency cannot emit electrons.
b)   λ = c / f
Therefore, as the wavelength increases, the frequency decreases and therefore the energy of the photoelectrons emitted, 
c)  threshold energy
         h f =Ф
Explanation:
It's photoelectric effect was fully explained by Einstein by the expression
        Knox = h f - fi
Where K is the kinetic energy of the photoelectrons, f the frequency of the incident radiation and fi the work function of the metal
a) True. The number of photoelectrons is proportional to the amount (intensity) of the incident beam. From the expression above we see that threshold frequency cannot emit electrons.
b) wavelength is related to frequency
          λ = c / f
Therefore, as the wavelength increases, the frequency decreases and therefore the energy of the photoelectrons emitted, so there is a wavelength from which electrons cannot be removed from the metal.
c) As the work increases, more frequency radiation is needed to remove the electrons, because there is a threshold energy
         h f =Ф