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Puchinita5
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Homework Statement
The three spheres in Fig. 13-45, with masses ma=80g ,mb=10g and mc=20g, have their centers on a common line, with L=12 cm and d=4cm. You move sphere B along the line until its center-to-center separation from C is d=4cm. How much work is done on sphere B (a) by you and (b) by the net gravitational force on B due to spheres A and C
Homework Equations
http://edugen.wiley.com/edugen/courses/crs1650/art/images/halliday8019c13/image_t/tfg045.gif
The Attempt at a Solution
I figured if W=Fd...then I started with trying to figure out the Force on particle b.
F= Gm1m2/rr so...
-G(.01)(.08)/(.04^2) + G(.01)(.02)/(.08^2) which gave me -3.13e-11...i then multiplied this by the distance d=.04...this gave me = -1.25e-12 J...
however the answer is .50 pJ
that's for net gravitational force, I'm not really sure how they mean for me to calculate the force by me?
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