why is the second law of motion important?

Answer 1

"II. The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors (as indicated by their symbols being displayed in slant bold font); in this law the direction of the force vector is the same as the direction of the acceleration vector." [See source.]

This law governs how all mass (e.g., your car, an airplane, a rocket, you) accelerates. Without acceleration all mass would simply stay at rest or move with a fixed velocity.

For example, without Law 2, you wouldn't be able to get up out of bed in the morning because your at-rest body would stay at rest. The force you exert with your muscles is what gets you accelerating out of bed. I'd guess getting out of bed is important to you.

Anything and everything that moves is governed by Newton's Second Law of motion. That goes all the way in scale from subatomic particles up through and including cosmic motion. Our planet revolves safely around the Sun rather than falling into it because of F=ma. I think that's about as important as you can get.

Answer 2

There are just too many reasons to tell you.

As you go to higher classes you will understand why.

90% or more of the equations that you will be using in chemistry and physics in higher classes will be somehow related to Newton's second law of motion.

Answer 3

Every acceleration (observable) is connected to a mass (fascination for matter) and a force (tells me what it is, I'm interested). Within one law, one get two very widely present properties. Energy is just behind matter and force. This is a very straight line towards our ultimate comprehension of the universe.
This even introduce us to the mathematical description of forces. Vector calculus is another fascinating field.

Answer 4

it's the most important one. It's the fundamental basis for calculating the movement of objects.

Answer 5

Because theres nothing wrong with second place :)