# Physics Notes On Force & Netwons’ Law

What is Force?

We define Force as:
1) Force is a push or pull.

2) Force is the capacity to do work or cause physical change.

3) Force= Mass times acceleration (F = ma)

4) A force is that which changes or tends to change the state of rest or
motion of a body.

Let’s See Some Examples here
For simplicity sake, all forces (interactions) between objects can be
placed into two broad categories: contact forces, and forces resulting from
action-at-a-distance.
also,
Contact Forces include frictional forces, buoyant forces, normal forces,
and air resistance forces….
while,
Action-at-a-distance forces include gravitation, electrostatic and magnetic
forces.

Measurement of Force
Force is measured using either the English System of Measurements or the
International System of Units (SI).
the most Common Units of Force are as following;
—>>SI: Newton (N) 1 N = 0.225 lb;
One Newton (N) of force is
defined as the amount of force needed to accede of mass at a rate of 1 meter per second squared (m/s^2).
1 Newton = 1 kg m/sec2 (A kilogram is the amount of weight at which 1 N of
force will accelerate at a rate of 1 m/s^2.)
—>>English System: Pound (LB) 1 LB = 4.448 N
In English system of measurements, a slug is the amount of mass that 1
pound of force will accelerate at 1 ft/s^2, and a pound mass is the amount of
mass that 1 LB of force will accelerate at 32 feet/s^2.

Description of a Force
A force is a vector quantity. A vector quantity is a quantity which has
both magnitude and direction. To fully describe the force acting upon an
object, you must describe both its magnitude and direction.
Thus we see, 10 Newtons of force is not a complete description of the force
acting on an object. 10 Newtons, downwards is a complete description of the
force acting upon an object.

Now we must learn What the
difference between vector and scalar quantities is?
A vector has both strength and
direction, a scalar quantity can be described using only 1 quantity, magnitude.
Example of vector quantities are
velocity, acceleration etc.
Examples of scalar quantities are
time, energy and volume since they only represent magnitude and no direction.

What is the Difference between
Mass and Weight?
Shown below are two types of
scales commonly used in the classroom –a spring scale (left) and a simple
balance beam scale on the right.
On earth the spring scale reads
100g with an unknown mass attached at the bottom. To balance the scale on the
right a 100g mass was also needed.
If we were to take both scales to the moon,
what would the the spring scale read? How much mass would be needed to balance
the 100g mass on the balance beam?

What does applying a Force do?
Force causes acceleration
Newton’s Second Law states that:
the acceleration (a) of an object is directly proportional to the force (F)
applied, and inversely proportional the object’s mass (m).
That means that the more force
you apply to an object, the greater the acceleration. And, the more mass the
object has, the lower the acceleration.

Newton’s Second Law can be
written in equation form:
F = ma.
For falling objects we can write
F=mg where g is the acceleration due to gravity. The force of gravity is what
causes free falling objects to accelerate. These objects all accelerate at the
same rate of 9.8 meters/sec^2.

What is Friction?
Friction is the force that
opposes the relative motion or tendency to such motion of two bodies in
contact. If we try to push a block of wood across a table, there are two
opposing forces that act: the force associated with the push, and a force that
is associated with the friction which acts in the opposite direction. As
frictional forces are decreased (for example, by placing oil on the table) the
object moves further and further before stopping. This demonstrates Galileo’s
law of inertia too.

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1. sam says:

@arushi mam??

2. Ayushi says:

Yes

3. sam says:

Gud morning mam….happy shivratri..F5

Thank u Ayushi mam for this valuable post …__/__

5. sam says:

Yeah..its really awsm

6. Ayushi says:

GA Sam. Thank You and same to u 🙂

gm sam

शिव की शक्ति, शिव की भक्ति, ख़ुशी की बहार मिले,
शिवरात्रि के पावन अवसर पर आपको ज़िन्दगी की एक नई अच्छी शुरुवात मिले!
शिवरात्रि की हार्दिक शुभकामनायें!

9. sam says:

fine and u

11. sam says:

Thanq mam…nd welcm

12. sam says:

Me as usual fyn…

13. sam says:

Hey,dear thanq nd wish u d same

ok,,
cgl 2015 ki preparation kaise chal rhi hai

15. sam says:

Yar,, I was focusing on bank po ,,bt ayushi mam k post se aisa feel ho raha hai kk from nw onwards I must prepare for cgl 2015 as well

have u given po interview?

17. sam says:

Dear I dint qualify…..bt did tym I will…

gud luck dear….

19. sam says:

U too shadow…may dis year v both will get job….

@arushi mam?

21. Ayushi says:

Good Morning mam…
happy shivratri…..

23. Ayushi says:

Thank You and same to you! 🙂

mam pls provide ECONOMY notes in pdf based on NCERT book

25. sam says:

Ayushi mam..plz fci ka syllabus nd previous year cut off jaroor post kriyega…it will help to achieve desired results to all of us

26. sam says:

27. Ayushi says:

We will try and post it Sam!

28. sam says:

Olryt mam…

29. Ayushi says:

Shadow we post questions related to economics.

As far as notes are concerned, we will try and make a post for it too!

thanks a lot mam __/__

yes

32. sam says:

Year meko ye btao k fci me generalist or depot k liye sirf 1 paper h na…120 questns nd 90 mints

33. career 195103 says:

What is approximate date of cgl 2014 tier 2?

34. Sandeep says:

It was scheduled to be held in January. Since it is postponed, official date is yet to be announced..

generalist or general

36. sam says:

Arey baba its understood na…olryt general..ab btao

yes paper 1 he hai

38. sam says:

Ok….nd graduation % ka koe issue to ne hai..means 69% must or smthing

40. विराट कोहली :)) says:

Thankyou mam/sir :))

41. Rohit says:

ssc adda also should be in hindi language

42. विराट कोहली :)) says:

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