This document provides an introduction to mechanics and the laws of motion. It defines key terms like kinematics, kinetics, mass, weight, and frames of reference for units. It describes the types of motion including displacement, speed, velocity, and acceleration. Newton's three laws of motion are summarized as well as concepts like force, linear momentum, and conservation of momentum. Specific examples are given to illustrate the first and second laws regarding changes in motion due to applied forces. The last law on action-reaction pairs is also briefly introduced.

1. PRESENTED
BY
D.RENUGA,
ASSISTANT PROFESSOR OF MATHEMATICS
SRI ADI CHUNCHANAGIRI WOMEN’S
COLLEGE,CUMBUM
THENI(DT)

2. INTRODUCTION
Mechanics: Deals with the action of forces on Bodies
Statics : Solids at rest.
Dynamics: The motion of Solid Bodies.
Hydrodynamics & Hydrostatics: The corresponding parts
of the subject dealing with fluids.
Dynamics divided into two parts
a)Kinematics b)Kinetics

3. INTRODUCTION
Kinematics: Deals with the different types of motion possible for a body
and the effects thereof on its position, in fact, the geometry of the motion ,
without considering the causes which produce motions.
Kinetics: Concerned with the effects of forces on the motion of bodies
Matter: It is anything which occupies space and can be perceived by our
senses.
Body: It is a portion of matter limited in all directions, having a finite
shape and size and occupying some definite space.
Particle: It is a portion of matter which is indefinitely small in size, so
small that the distance between the different parts of it may be
neglected. Here that is materials.

4. INTRODUCTION
Mass: It is the quantity of matter in the body.
Weight:The weight of a body is the force with which the earth attracts it.
F.P.S: foot – pound - second
C.G.S: centimetre-gram-second
M.K.S: metre-kilogram-second
Kinematics:
a) Displacement b)Speed c)Velocity d)Acceleration
a)Moving point in any interval of time is its change of position.
ie)ds=s2-s1
b)Moving point is the rate at which it describes its path without any
reference to its direction of motion. (Types:uniform, average) ie)
c)A moving point is the rate of its displacement ie) v=ds/dt
d)A moving point is the rate of change of its velocity. ie)f=dv/dt

5. INTRODUCTION
Retardation: If acceleration is in a direcrion opposite to that of motion of a
particle.
Motion in a straight line under uniform acceleration: A particle moves
along a straight line starting with velocity u and having a constant
acceleration f in its direction of motion. If v is its velocity after time t and
s is the distance described by it during that time, then
v=u+at …………………..(1)
s=ut+1/2ft^2………………(2)
v^2=u^2+2fs………………(3)
Note: When a particle starts from rest, u=0 then
v=ft
s=1/2ft^2
v^2=2fs

6. INTRODUCTION
Vertical motion under gravity: The particle is subject to retardation g, then putting f=-
g in the equations of motion with uniform acceleration
v=u-gt …………………..(1)
s=ut-1/2gt^2………………(2)
v^2=u^2-2gs………………(3)
Note: At the highest point , the velocity must be zero. Then
(1) becomes u=gt this implies t=u/g
(3) becomes u^2=2gs this implies that s= u^2/2g
Bodies freely falling downward:
initial velocity u=0 and height(s)=h and putting f=g then
v=gt………………………..(1)
h=1/2gt^2…………………..(2)
v^2=2gh this implies that Final velocity=sqrt(2gh)….(3)

7. UNIT –I
THE LAW OF MOTION
INTRODUCTION
CONCEPTS:
•FORCE
•LINEAR MOMENTUM
•NEWTON’S LAWS
•F=mf
•PHYSICAL INDEPENDENCE OF FORCES
•PARALLELOGRAM LAW OF FORCES
•CONSERVATION OF LINEAR MOMENTUM
•NORMAL REACTION
•FORCE OF FRICTION
•COEFFICIENT OF FRICTION
•MOTION- ROUGH HORIZONTAL PLANE
•MOTION- ROUGH INCLINED PLANE
•PRESSURE OF A BODY-RESTING ON

8. UNIT –I
THE LAW OF MOTION
•FORCE:
It is any cause which produces or tends to produce a change in the existing
state of rest of a body or its uniform motion in a straight line. It has magnitude and
direction and therefore a vector quantity.
•LINEAR MOMENTUM:
The linear momentum of a body of mass m and whose velocity is V is the
vector mV
•NEWTON’S FIRST LAW
1)Every body continues in its state of rest or of its uniform motion in a
straight line , unless it is compelled by any external impressed force to change that
state.
Examples:
(I) One's body movement to the side when a car makes a sharp turn.
(ii)Tightening of seat belts in a car when it stops quickly.

9. UNIT –I
THE LAW OF MOTION
(iii)A ball rolling down a hill will continue to roll unless friction or another
force stops it.
(iv) If pulled quickly, a tablecloth can be removed from underneath of dishes.
NEWTON'S SECOND LAW
2)The rate of change of momentum of a body is proportional to the
impressed force and takes place in the direction in which the force acts
Examples:
(a)Try to move an object.
(b)Pushing a car and a truck.
(c) · Racing Cars.
(d)Rocket launch.
(e)Kick the ball.
(f)Car crash.

10. •Examples:
•g)· Two people walking.
(h)Object thrown from a height
NEWTON'S THIRD LAW:
3)To every action there is always an equal and opposite reaction or the
mutual actions of any two bodies are always equal and oppositely directed.
Examples:
(i)Firing of a bullet: When a bullet is shot from a gun, the gun puts a force on the
bullet that propels it forward. ...
(ii)A book lying on a table: The weight of the books is acting in the downward
direction on the table (action). ...
(iii)During swimming, a swimmer moves ahead.

11. THANK YOU