Answer:
8
Explanation:
Groups go down, periods go across :)
Answer:
The value is 
Explanation:
From the question we are told that
The value of charge on each three point charge is

The length of the sides of the equilateral triangle is 
Generally the total potential energy is mathematically represented as
![U = k * [ \frac{q_1 * q_2}{r} + \frac{q_2 * q_3}{r} + \frac{q_3 * q_1}{r} ]](https://tex.z-dn.net/?f=U%20%20%3D%20k%20%2A%20%20%5B%20%5Cfrac%7Bq_1%20%2A%20%20q_2%7D%7Br%7D%20%20%2B%20%20%5Cfrac%7Bq_2%20%2A%20%20q_3%7D%7Br%7D%20%20%20%2B%20%5Cfrac%7Bq_3%20%2A%20%20q_1%7D%7Br%7D%20%5D)
=>
Here k is coulomb constant with value 
=>
The situation given above can be answered through the concept of the First Law of thermodynamics which states that the change in internal energy is equal to the difference between the work done and the heat added to the system. The work done by the object is negative and the heat added is positive.
change in internal energy = -500J + 1400 J = 900 J