physics help please?!?(i need explanations not answers)?

[princess]

1. A pendulum with a string length of 42.66 cm swings back and forth. You push it whenever it has come to rest at a turning point. With which frequency do you have to push it in order to cause resonance, that is maximal energy build up in the oscillation ?

2. A 0.735 kg block attached to a spring with a spring constant of 34.28 N/m oscillates frictionless with an amplitude of 0.2604 m on a horizontal plane. What is the maximum velocity of the block ?

3. A spring with a spring constant of 44.59 N/m which is aligned vertically is compressed by 11.29 cm from its relaxed state. A 0.0604 kg mass is then placed on the spring and the spring is released. What is the kinetic energy of the mass as it lifts off from the relaxed spring ?

4. A compressed spring with a spring constant of 160.1 N/m has 7.531 J potential energy stored in it. How far is the spring compressed from its relaxed state?