Answer:
The system's potential energy is -147 J.
Explanation:
Given that,
Energy = 147 J
We know that,
System is isolated and it is free from external forces.
So, the work done by the external forces on the system should be equal to zero.

We need to calculate the system's potential energy
Using thermodynamics first equation

Put the value into the formula


Hence, The system's potential energy is -147 J.
 
        
             
        
        
        
Answer:
Explanation:
Momentum change for either skater is mΔv = 75.0(5.0) = 375 kg•m/s
As a change in momentum is equal to an impulse
375 = FΔt
F = 375/0.100 = 3750 N
As 3750 N < 4500 N no bones are broken. 
 
        
             
        
        
        
Choice-C is a correct statement.
        
                    
             
        
        
        
We have that the electric field at the center of the metal ball due only to the charges on the surface of the metal ball is

From the question we are told that
A solid metal ball of radius 1.5 cm 
bearing a charge of -15 nC is located near a hollow plastic ball of radius 1.9 cm bearing 
 uniformly distributed charge of -7 nC
The distance between the centers of the balls is 9 cm
Generally the equation for the electric field  is mathematically given as


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