Answer:
-17.5 nC
Explanation:
charge A = -30 nC
charge B = -5 nC
After adding them it would be the average of the two charges because of the getting same voltage difference. so
c = (-30+(-5)) / 2 nC
c= -17.5 nC
answer is -17.5 nC
 
        
             
        
        
        
Answer:
q = 0.036 C
Explanation:
Given that,
Current passes through a defibrillator, I = 18 A
Time, t = 2 ms
We need to find the charge moved during this time. We know that,
Electric current = charge/time

Put all the values,

So, 0.036 C of charge moves during this time. 
 
        
             
        
        
        
Answer: #4 
Sally is faster.
Explanation:
If you multiply Sallies it is going to be less than Jessica's.
 
        
             
        
        
        
Answer:
The magnitude of force per unit length of one wire on the other is  and the direction is away from one another
 and the direction is away from one another
The magnitude of force per unit length of one wire on the other is  and the direction is towards each other.
 and the direction is towards each other.
Explanation:
 = Vacuum permeability =
 = Vacuum permeability = 
 = Current in first wire = 2.9 A
 = Current in first wire = 2.9 A
 = Current in second wire = 5.3 A
 = Current in second wire = 5.3 A
r = Gap between the wires = 11 cm
Force per unit length

The magnitude of force per unit length of one wire on the other is  and the direction is away from one another
 and the direction is away from one another

The magnitude of force per unit length of one wire on the other is  and the direction is towards each other.
 and the direction is towards each other.
 
        
             
        
        
        
Answer:
933. 3kg
Explanation:
We are given that 
Mass,m=2000 kg
Initial speed,u=4.4 m/s
We have to find the maximum mass of grain if the speed of loaded freight car must not go below 3.0 m/s.
Final speed,v=3 m/s
By conservation of momentum 
Initial momentum=Final momentum

Substitute the values



Mass of freight loaded car=2933.3 kg
Mass of grains=2933.3-2000=933.3 kg
Hence, the maximum  mass of grains that it can accept=933.3 kg