In Cavendish's experiment, let each small mass be `20g` and each large mass be `5kg`. The rod connecting the small masses is `50cm` long, while the small and the large spheres are separated by `10.0cm.` The torsion constant is `4.8xx10^(-8) kg m^2 s^(-2)` and the resulting angular deflection is `0.4^@`. Calculate the value of universal gravitational constant `G` from this data.

Explanation

Here `m=20 g=0.02 kg, M=5kg`
` r=10cm=0.1m,l=50cm=0.5m`
`theta=0.4^(2)=(0.4^(@))(2pi//360^(@))=0.007^("rad")`
`k=4.8xx10^(-8)kgm^(2)s^(-2)`
Thus from `G=(k theta r^(2))/(Mml)`
`G=((4.8xx10^(-8))(0.007)(0.1)^(2))/(5xx0.02xx0.5)`
`=6.72xx10^(-11)Nm^(2)kg^(-2)`