Câu 1 giải như thế nào

What is the momentum of a 2 kg object moving at 15 meters per second

Apulley with mass mp and a radius rp is attached to the ceiling, in a gravity field of 9.81 m/s2 and rotates with no friction about its pivot.

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?