If a 0.9 kg object hanging from a spring stretches it by 0.60 m, then by how much will the spring be stretched (in m) if a 1.8 kg object is suspended from it?

Acapacitor is storing energy of 3 joules with a voltage of 50 volts across its terminals. a second identical capacitor of the same value is storing energy of 1 joule. what is the voltage across the terminals of the second capacitor?