Um pêndulo consiste em uma bola de massa m presa a um fio de comprimento L. A ball is pulled until the wire forms an angle θo with a vertical. So it's dropped from

rest as shown in a figure. Neglect air resistance.

a) Show that the work done by the tension in the wire is zero.

b) Voltage is the only non-conservative force acting on the system. The fact does

work done by the voltage is null, implies in the conservation of energy

mechanics? Justify!

c) Determine a literal expression for the speed of the ball at the lowest point of the

trajectory as a function of the parameters θ and L given. Tip: make a diagram of

free body to facilitate.

d) Determine a literal expression for the module of the thread tension, at the most

down the trajectory according to the parameters θ and L given. .

Tip: Make a free-body diagram for ease