Answer:
We show added energy to a system as +Q or -W
Explanation:
The first law of thermodynamics states that, in an isolated system, energy can neither be created nor be destroyed;
Energy is added to the internal energy of a system as either work energy or heat energy as follows;
ΔU = Q - W
Therefore, when energy is added as heat energy to a system, we show the energy as positive Q (+Q), when energy is added to the system in the form of work, we show the energy as minus W (-W).
 
        
             
        
        
        
Answer:
20 kg
Explanation:
remember the equation f=ma. 
100 N=force
5 m/s2= acceleration
so you need to divide force by acceleration: 100 N/ 5 m/s2= 20 kg, to get the mass. 
 
        
             
        
        
        
The correct is  Reverberation. A reverberation is created when a sound or signal is reflected causing a large number of reflections to build up and then decay as the sound is absorbed by the surfaces of objects in the space – which could include furniture, people, and air. 
        
                    
             
        
        
        
The volume of every sphere is
           Volume = (4/3) (pi) (radius)³
When you say "across", I think you mean the diameter of the ball.
The radius is half of the diameter = 12 inches.
         Volume = (4/3) (pi) (12 inches)³
                       = (4/3) (pi) (1,728 cubic inches)
                       =    7,238.2 cubic inches .  (rounded) 
        
             
        
        
        
Pressure difference (voltage) 
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