Question

(a) A sphere is attached to a thread of length L = 24.3 cm and suspended from the ceiling, as shown in the figure. A uniform electric field points to the right in the figure, when θ = 16.0°, the sphere is in equilibrium. Find the net charge on the sphere (in μC)

_______ μC

(b) What If? If the electric field is suddenly turned off, what is the speed of the sphere at the bottom of its swing (in m/s)? 

_______  m/s 

Answer 1

Answer 2

the other answer gives you the wrong solution to part b, you need to use conservation of energy ( k=.5mv^2) and you can substitute the kinetic energy (k) with potential energy which is equal to mgh so you use the equation mgh = .5mv^2 and you do some algebra to get the equation v = sqrt((2mgh)/m). you can find h using trigonometry where h = l*cos(theta).