Answer:
5N
Step-by-step explanation:
The formula formula for calculating the force between charges is expressed as;
F = kq1q2/r²
If two charges are separated by a distance r and a force between them is 45N, then;
45 = kq1q2/r² ....1
If the distance between the charges is tripled to 3r, then;
F = kq1q2/(3r)²
F = kq1q2/9r² ... 2
Divide both expressions
45/F = (kq1q2/r²)/(kq1q2/9r²)
45/F = kq1q2/r² * 9r²/kq1q2
45/F = 9
9F = 45
F = 45/9
F = 5N
Hence the new force between them will be 5N