The first one just confuses me because of the word in the brackets. 1. A 70kg boy stands 1.0 m away from a 60 kg girl. Find the force of attraction (gravitational) between them. For this would I just sub the values into F=Gm1m2/r^2? The second question is giving me a lot of problems. 2. How fast would the earth (r=6400km) have to be spinning befor a 100kg person would exert no force on a scale at the equator? Assume the earth is a perfect sphere and it's mass is 6.0 * 10^24 kg. For this I took F=ma and subbed in a=4 (pi)^2 r / T^2. Then I made F=0 and solved for T, but my answer gave me a period of 44 hours. This can't be write since it would have to be spinning faster than 24 hours. Please help.