Why do wee see lightning before we hear thunder?

Idon’t quite understand this problem

Which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?

Auniform crate c with mass mc is being transported to the left by a forklift with a constant speed v1. what is the magnitude of the angular momentum of the crate about point a, that is, the point of contact between the front tire of the forklift and the ground