The expression for the voltage across a 2 F capacitor is given below: v(t) = 2t mV, for0t 5s
v(t) = 10e - (t - 5) mV, for5t 
Derive the expressions for and carefully sketch and label the current through i(t) and the energy stored W(t) in the capacitor for 0  t  infinity.

Ahelical coil spring has a mean diameter of 50 mm, a wire diameter of 5.5 mm and is wound with a pitch of 10 mm. the spring steel has an ultimate strength of 1250 mpa. find the force needed to compress the spring solid and the wire stress in this condition. state whether the spring will return to its initial length.