Gravitational acceleration is approx 9.8 m/s
Time is 7s
a=9.8 m/s
t=7s
a = d/t^2
therefore:
d = a * t^2
d = 9.8 * 7^2
d = 9.8 * 49
d = 480.2 [m]
 
        
             
        
        
        
Answer:
This can be translated to:
"find the electrical charge of a body that has 1 million of particles".
First, it will depend on the charge of the particles.
If all the particles have 1 electron more than protons, we will have that the charge of each particle is q = -e = -1.6*10^-19 C
Then the total charge of the body will be:
Q = 1,000,000*-1.6*10^-19 C = -1.6*10^-13 C
If we have the inverse case, where we in each particle we have one more proton than the number of electrons, the total charge will be the opposite of the one of before (because the charge of a proton is equal in magnitude but different in sign than the charge of an electron)
Q = 1.6*10^-13 C
But commonly, we will have a spectrum with the particles, where some of them have a positive charge and some of them will have a negative charge, so we will have a probability of charge that is peaked at Q = 0, this means that, in average, the charge of the particles is canceled by the interaction between them.
 
        
             
        
        
        
Answer:
If one side of the train is positive and the other is negative they will attract if they are the same then they will repel. 
Explanation:
If both are positive they will repel if both are negative they will repel and if they are opposites they will attract.
 
        
                    
             
        
        
        
Answer:
They both have the same angular speed.
Explanation:
The mathematical formula for angular speed is:

where  is angular speed,
 is angular speed,  is a constant, and
 is a constant, and  is the period (the time it takes the marry-go-round to complete a lap).
 is the period (the time it takes the marry-go-round to complete a lap). 
What we can see from the formula is that, since the  does not change its value, the angular speed depends only on the period T.
 does not change its value, the angular speed depends only on the period T.
In this case for both the children closer to the outher edge and for the children closer to the center, the time to complete a lap is the same, because the time does not depend on where they are sitting in the marry go round. This means that the period for both is the same.
Thus, since the period for both is the same, the angular speed given by
 will also be the same
 will also be the same