The vertical velocity?

Find v(t), given acceleration a(t)=7j and initial velocity v(0)=k

A2.00-m long piano wire with a mass per unit length of 12.0 g/m is under a tension of 8.00 kn. what is the frequency of the fundamental mode of vibration of this wire?

What is the weight of a feather (mass = 0.0001 kg) that floats through earth's and the moon's atmospheres?