Kinetic energy and momentum.

Ek = 0.5mv^2
P=mv

m=1, v=1
Ek = 0.5

m=1, v=2
Ek = 2

Accelerating a 1 kg object to 1m/s requires 0.5 joules whilst accelerating it a further 1m/s to 2m/s requires an additional 1.5 joules. Why is this?

>>3
How does that explain why in one instance it takes 0.5 joules to accelerate 1m/s whilst in another it takes 1.5 joules? If you are in a rocket in a vacuum with an engine that uses the same amount of energy per second, does this mean that acceleration decreases as you go faster?