This document discusses several topics in mechanics including dynamics, projectiles, collisions, trajectories, and simple harmonic motion. Dynamics is defined as the branch of mechanics concerned with the effects of forces on motion, especially external forces. A projectile only experiences the force of gravity, causing vertical acceleration, while horizontal motion remains at constant velocity. The angle and velocity of projection determine a projectile's path. Collisions represent interactions between particles via forces, with kinetic energy conserved in elastic collisions. Trajectories describe the path a particle takes. Simple harmonic motion involves oscillations where acceleration is directed towards a fixed point and is proportional to distance from that point, like a pendulum or plucked string.

1. DYNAMICS
M.MOHANA MALAR. M.Sc., M.Phil.
N.MALATHI. M.Sc.

2. The branch of mechanics that
is concerned with the effects of forces on the
motion of a body or system of bodies,
especially of forces that do not originate
within the system itself. That is the external
forces and not the internal ones.

3. Projectile
A projectile is an object upon
which the only force is gravity. Gravity acts to
influence the vertical motion of the projectile,
thus causing a vertical acceleration. The
horizontal motion of the projectile is the
result of the tendency of any object in motion
to remain in motion at constantvelocity.

4. Theangle of projectionis the
angle that the directionin which the particle
makes with the horizontalplane throughthe
pointof projection.
The velocityof projectionis the
velocitywithwhichthe particle is projected.

5. Collision
Term collision is used to represent
an event during which a particle come close
to each other and interact by means of forces.
Kinetic Energy is conserved in elastic
collisions. There are instances that are very,
very closeto perfectlyelastic collisions.

6. The trajectory is the pathwhich
the particledescribes.
The range on a plane throughthe
pointof projection
Thetime of flight is the interval
of time that elapsesfrom the instantof
projectiontill the instantwhenthe particle
again meets the horizontalplane throughthe
pointof projection.

7. Simple Harmonic Motion
When a particle moves in a
straight line so that its acceleration is
always directed towards a fixed point in
the line and proportional to the distance
from that point , its motion is called
Simple Harmonic Motion.

8. Theperiodor the periodictime of a
simpleharmonicmotionis the interval of time
that elapsesfrom any instanttill a subsequent
instant whenthe particleis again moving
through the same positionwith the same
velocityin the samedirection.

9. The oscillations of a simple
pendulum and the transverse
vibrations of plucked violin
string are examples of simple
harmonic motion.

10. Thank You