Answer:
2.3 Nm clockwise
Explanation:
Take counterclockwise to be positive and clockwise to be negative.
∑τ = (3 N) (2.5 m) − (7 N) (1.4 m)
∑τ = 7.5 Nm − 9.8 Nm
∑τ = -2.3 Nm
The net torque is 2.3 Nm clockwise.
 
        
             
        
        
        
The answer is A, it breaks down and releases thermal energy. 
        
                    
             
        
        
        
Answer
D.Diffraction
Explanation
Diffraction is a property that is experienced by waves when they come across a barrier when they are in motion. 
The ways tends to curve behind the barrier. This is called diffraction of waves.
Now, sound is a wave and it also experience diffraction. . So the brother will be able to hear the sound due to diffraction
 
        
                    
             
        
        
        
Explanation:
If a metal rod of length L moves with velocity v is moving perpendicular to its length, in a magnetic field B, the induced emf is given by :

The electric field in the conductor is given by :

It is clear that the electric field is independent of the length of the rod. If the length of the rod is doubled, the electric field in the rod remains the same.
 
        
             
        
        
        
Answer:
Vapors 
Explanation:
We take into account that all the energy from the lightning has been transformed into steam. 

We calculate the amount of energy required by water to convert into steam.



From the lightning we received  of energy, out of which
 of energy, out of which  has been used to convert the water into steam.
 has been used to convert the water into steam.
Energy left = 
We use this energy to convert steam into vapors. 


With this temperature, we can easily interpret that the vapors will be dissociated in hydrogen and oxygen particles.