Calculating Gravitational Force Between a Doctor and a Baby

[Rasine]

Some believe that the positions of the planets at the time of birth influence the newborn. Others deride this and say that the gravitational force exerted on a baby by the obstetrician is greater than that exerted by the planets. To check this claim, first calculate the gravitational force exerted on a 5.7 kg baby by a 87.9 kg doctor who is 1.0 m away.


ok so i am going to use the formula F=G(m1m2)/r^2 and that would be

F=6.67x10^-11(87.9*5.7)/.5^2 which yeilds 1.32 x10^-7 N which is not the right answer

what am i doing wrong

 

[hage567]

You have 0.5 for your distance. It should be the 1 m. It is the total distance between the objects you need here.

 

[denverdoc]

time to call in a replacement--seriously if the center of gravity between the doc and the mom is a meter, those are long forceps. just a joking aside.

 

[Rasine]

the equation calls for the radius squared and so i was using .5^2

 

[denverdoc]

the equation calls for the radius squared and so i was using .5^2

I think the radius is the distance between the two objects centers. This is different than how we usu think of circles and distance.