Posted by JulieAnne on Wednesday, January 5, 2011 at 5:15pm.

Question

Please check my two answers


I was sitting in a park on a bench next to another person and I moved tow times the original distance between the two of us, the force of gravity between me and the other person would be:
1. one-quarter as much
2. one-half as much
3. twice as much
4. 4 times as much

I think it would be one-half as much because the force of gravity diminishes the farther you get away from object, correct or no?

2. If Earth's mass was increased by 4 times the amount, remain the same distance from the sun, would the speed of the Earth:
stay the same
increase by factor of 4
decrease by factor of 2
increase by factor of 2

I think it would stay the same, correct?

Answer 1

1) Yes, the gravitational force diminishes the farther you get, but by what factor? Check the equation.

2) The speed of the earth keeps it in orbit around the sun. Changing the mass changes the gravitational force, which is also the centripetal force for the orbit.

Answer 2

1 no, goes as 1/d^2 = 1/4

2. correct, Mearth cancels
G Me Ms/r^2 = Me v^2/r

Answer 3

Thank you for the explanation, Damon