Two small metallic spheres, each of mass 0.15 g are suspended as pendulums by li

Question

Two small metallic spheres, each of mass 0.15 g are suspended as pendulums by light strings from a common point as shown. The spheres are given the same electric charge, and it is found that the two come to equilibrium when each string is at an angle of 6.1 with the vertical. If each string is 25.8 cm long, find the magnitude of the charge on each sphere. The Coulomb constant is 8.98755 × 109 N · m2 /C 2 and the acceleration of gravity is 9.81 m/s 2 . Answer in units of nC.   

Could someone please show me step by step how to solve this? I honestly don't know where to start.

Explanation / Answer

The distance between the two sphere

tan A = f/w = {kQ^2/r^2}/{mg} = kQ^2/(mgr^2)

now Q = [4mgl^2*(sinA)^2*tanA/k]^0.5

Q= [4*0.15*10^3*9.81*0.258^2*(sin 6.1)^2*tan 6.1/(9*10^9)]^0.5

=>Q= 7.24*10^-6 C

7.24 nC answer

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.