Three equal point charges, each with charge 1.45 μC , are placed at the vertices of an equilateral triangle whose sides are of length 0.400 m . What is the electric potential energy U of the system? (Take as zero the potential energy of the three charges when they are infinitely far apart.)

Explanation:

The electrostatic potential energy for a pair of charge is given by:

Hence for a system of three charges the electrostatic potential energy can be found by adding up the potential energy for all possible pairs of charges.For three equal charges on the corner of an equilateral triangle,the electrostatic energy given by:

Substitute the values as q=1.45μC and r=0.400m

So

when jerome paddle in flowing river towards east the net speed of jerome will increase

so the net speed of jerome will be given as

now the speed of paul will be same as it is given as he is running on the ground

so

so here we can say since the speed of jerome is more so he will win the race

now as we know the distance so the time difference is given as

so jerome will reach first and the time difference will be 203.55 s or 3.4 min