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https://s4.lite.msu.edu/res/msu/mmp/kap18/picts/pith.gif Two small pith balls, e

ID: 2284225 • Letter: H

Question

https://s4.lite.msu.edu/res/msu/mmp/kap18/picts/pith.gif

Two small pith balls, each of mass m = 14.7 g, are suspended from the ceiling of the physics lab by 1.5 m long fine strings and are not moving. If the angle which each string makes with the vertical is ? = 21.4

https://s4.lite.msu.edu/res/msu/mmp/kap18/picts/pith.gif

Two small pith balls, each of mass m = 14.7 g, are suspended from the ceiling of the physics lab by 1.5 m long fine strings and are not moving. If the angle which each string makes with the vertical is ? = 21.4

Explanation / Answer

sum forces in the y

T cos theta - m g = 0

T = m g/cos theta

sum in the x

F electric - T sin theta = 0

k q^2/r^2 - m g tan theta = 0

9.0E9*q^2/(2*1.5*sin(21.4 degrees))^2 - 14.7E-3*9.81*tan(21.4 degrees)=0

q=2.74E-6 C = 2.74 uC