Several questions on Newton ?

[Progression]

Hello, I am pretty new to the study of science and I was just reading an article on wikipedia about Newtons laws . I have a few questions on this and hoped somebody would kindly answer . 

 

 

Quote

Newton's laws of motion are three physical laws that, together, laid the foundation for classical mechanics. They describe the relationship between a body and the forces acting upon it, and its motion in response to those forces. More precisely, the first law defines the force qualitatively, the second law offers a quantitative measure of the force, and the third asserts that a single isolated force doesn't exist. These three laws have been expressed in several ways, over nearly three centuries,^[a] and can be summarised as follows:

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First law:	In an inertial frame of reference, an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force.[2][3]
Second law:	In an inertial frame of reference, the vector sum of the forces F on an object is equal to the mass m of that object multiplied by the acceleration a of the object: F = ma. (It is assumed here that the mass m is constant – see below.)
Third law:	When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.

 

 

From: https://en.wikipedia.org/wiki/Newton's_laws_of_motion

What does it mean by a quantitative measure of force ? 

What is an inertial reference ? 

Is there a Law on acceleration ?

 

Edited November 22, 2019 by Strange
Took the liberty of moving the questions out of the quote (and adding citation)

[Mordred]

Quantitative means you can assign a unit of measure. In this case quantify into units of Newton's.

An inertial reference is one of constant velocity. 

There is no Law of acceleration however there is treatments for acceleration using instantaneous velocity or alternatively mean average velocity between initial and final velocity.

Edited November 21, 2019 by Mordred

[Strange]

I would say that Newton's second law is the nearest thing we have to a law of acceleration. Although there are other, related, "laws" (in the general sense of a mathematical relationship) such as the kinematic equations: https://www.khanacademy.org/science/physics/one-dimensional-motion/kinematic-formulas/a/what-are-the-kinematic-formulas

[swansont]

You don't need a law for acceleration because you have laws for force, and for a system of constant mass, force and acceleration are directly related via the mass. F = ma. They behave the same way.

[Strange]

18 hours ago, Progression said:

What does it mean by a quantitative measure of force ? 

The intro says: "the first law defines the force qualitatively, the second law offers a quantitative measure of the force"

Note the difference between the first and second laws. The first one just says that the velocity will "change" if acted on by a force. It doesn't say in what way it will change or by how much it will change. Just "change". So this is a qualitative description. The second law provides a mathematical relationship between the applied force and the change in velocity (ie the acceleration). This means you can apply numbers to any two of the components (mass, acceleration or force) and calculate the magnitude (and, if relevant, direction) of the third. This is therefore a quantitative description.

This distinction is very important in science, especially physics. A purely qualitative description is hard (perhaps impossible) to test. A quantitative (ie a mathematical) description can predict precise values that should be measured by an experiment. So this is the basis of rigorous science.