Here is the ex. in the book. Two 3.kg textbooks are .15 apart. What is the gravitational attraction? The answer is given 2.7*10-8 I also know the formula is F=Gm1m2/r I just do not understand what they are doing to get the answer. (6.67*10-11 N-m2kg2)(3.kg)(3.kg)/.15 This is the formula I am trying to use Please help!