# Why Newton’s Second Law is So Important?

By | July 6, 2017

If we push an object and it starts to move, how fast would it move?

If its pushed harder, how much faster does it move?

How does the velocity of the object change?

Or will the change of velocity with respect to time follow a certain rule?
Before Newton nobody really knows what is the relationship between force and the change in velocity, if any.

However its important to know certain details in order to make an accurate prediction.

For instance, if a train moves at 100 km/h then we can say with a high degree of certainty that within three and half hour, the train will travel an equivalent of 350km.

At least you know when is the right time to wait for someone if you happen to have these important details.
On the other hand an object moving with constant velocity is kind of virtually impossible in the real world.

Friction opposes motion and slows down the velocity of an object moving on a rough surface.

Therefore when you roll an object on the floor it will slow down and eventually stops simply because of the existence of friction.

If friction is reduced, perhaps by mopping the floor first then the ball will travel a longer distance before stopping.
Objects move quicker too when pushed harder.

Objects slow down when they experience friction.

The variation of the velocity experienced by the object within a period of time is called acceleration.
Yet no one before Newton could formulate a mathematical equation to describe the relationship between forces and motion.

So it is strange indeed that during those times we do not know exactly how forces would affect motion in a quantitative manner.
The blurry and incomplete understanding of forces and motion was replaced by a crystal clear understanding after Newton introduced his second law of motion.

Basically it states that an object will accelerate when it experience a net external force imposed upon it.

However what makes the law more deterministic in nature is simply because now we are able to calculate the acceleration in a more precise manner since the value of the acceleration is equivalent to the ratio of the external force divided by the mass of the objective itself.
In a single stroke Newton’s laws allow all of us to determine in a more precise manner how motion is related to force. We are able to calculate and make predictions in a more confident manner as ambiguity is no longer an issue.
Then again Newton’s second law is a vector equation.

Therefore there is a need to consider the direction of the forces as well. If you add the magnitude of three and four you will get seven.

However if you add three and four yet three is in a horizontal direction while four is in the vertical direction then the answer is five.

On the other hand the direction is neither horizontal or vertical. Add three and four and you get five? That’s the weird world of vector.
Then came along the idea of momentum, a product where the mass multiply by the velocity of the object will give rise a value defined as momentum.

With mathematical manipulation, Newton’s Second Law suddenly can be described in a more subtle manner.

It is now equivalent to the rate of change of momentum. Sounds so bombastic isn’t it?
Yet as we know in life there is a limit to everything.

Newton’s Second Law has a limitation too. It somehow only works for objects that do not scream ahead at a very high speed. How high is high then?

Well, the speed we are talking about is near the speed of light.

Light is a faceless entity that moves at 300,000 metres in one second.

Can you imagine that?

Since most of the things that we observe in real life do not move at such a high speed therefore Newton’s Second Law continue to reign supreme.
What law does an object that moves nearly the speed of light adhere too?

Well, that’s another story for another day I guess.