Answer;
-  No, Two vectors of unequal magnitude can never sum to zero. 
Explanation;
-Two vectors of equal magnitude that are pointing in opposite directions will sum to zero.
-Two vectors of unequal magnitude can never sum to zero. If they point along the same line, since their magnitudes are different, the sum will not be zero.
- If they point in different directions, then you can always decompose one vector into two components: one along the other vector and one perpendicular to the other vector. In this case, the perpendicular component can never be eliminated.
 
        
             
        
        
        
Answer:

Explanation:
Givens



The frequency is defined by

Where  is the speed of the wave in the string and
 is the speed of the wave in the string and  is its wave length.
 is its wave length.
The wave length is defined as 
Now, to find the speed, we need the tension of the wire and its linear mass density

Where  and the tension is defined as
 and the tension is defined as 
Replacing this value, the speed is

Then, we replace the speed and the wave length in the first equation

Therefore, the frequency is 
 
        
                    
             
        
        
        
Answer:
5) Displacement = +3.125 m
Displacement is in the same direction as the force vector. 
6) Force = -53.89 N
Force is in an opposite direction relative to the displacement. 
Explanation:
5) We are given;
Force; F = 160 N. 
Workdone; W = +500 J
Now, formula for workdone is;
W = Force × displacement 
Thus, displacement = Work/force
Displacement = 500/160
Displacement = +3.125 m
Thus, displacement is in the same direction as the force vector. 
6) We are given;
Displacement; d = 18 m. 
Workdone; W = -970 J
Like in the first answer above, 
Workdone = Force × Displacement
Thus; 
Force = Workdone/Displacement
Force = -970/18
Force = -53.89 N
Since force is negative and displacement is positive, it means force is in an opposite direction relative to the displacement. 
 
        
             
        
        
        
Answer: The Electrostatic force of attraction or repulsion between two charges shows that the Newton's third law applies to electrostatic forces.
Explanation: Consider two Oppositely charged charges separated by distance d. 
The electrostatic force exerted by charge 1 on charge 2 is.
 By Coulomb's Law :
                F1  = k  .....................................(1)
.....................................(1)
The electrostatic force exerted by charge 2 on charge 1 is.
               F2  = - k  ................................. (2)
 ................................. (2)
negative sign shows that force are in opposite direction.
  
 From Equation 1 and 2 
               F1 = - F2
Which implies Newton Third law.
 
        
             
        
        
        
Pretty sure physical, a chemical change would be something of the time of acid rain, meanwhile physical changes are the ones that affect the form not the actual chemical composition