The answer to the question is friction
Solution :
Given :
Mass of the object attached to the spring, m = 2 kg
Velocity of the object as it moves, V = 5 m/s
Amplitude of the object as it swings, A = 2.5 m
We have to find the frequency of the object.
We known,

Therefore, 

f = 0.32 Hz
Therefore the frequency of the object is 0.32 hertz when the amplitude of the 2 kg mass is 2.5 m moving a speed of 5 m/s.
B)natural selection
Darwin discovered this idea of natural selection while on a voyage to places such as the Galapagos Islands. Essentially, the idea is that certain animals developed traits that allowed them to survive better than others.
Use the formula for mechanical advantage of simple machines. As for a lever, use formula below
mechanical advantage = force output/force input
where
Force input = 330 N
mechanical advantage = 1.6
substitute all the given data, we will get Force output
Force output = 528 N