Physics - the study of matter, energy and their interactions - is an international enterprise, which plays a
key role in the future progress of humankind
Motion of objects – living and non-living matter - is one of the key branches of physics. It finds
applications in numerous fields such as engineering, medicine, geology, and sport science among
others. Whether you drive (or you are driven), walk, jog or fly in the air, you are exercising some form of
motion. When in this state, habitually one is interested in how much longer, when, and how quickly one
can get to his / her destination.
Variables
Distance: is a change in position relative to a reference (or zero) point. (SCALAR)
Displacement: is a change in position relative to a reference (or zero) point in a particular direction.
(VECTOR)
Average Speed: is the rate of change of distance. (SCALAR)

instantaneous speed: When we refer to the speed at a given point in time, we are talking about
what is ‘technically
Average Velocity: is the rate of change of displacement (VECTOR)

Velocity at a specified position or a particular point in time is called instantaneous velocity
Average Acceleration: is the rate of change of velocity (VECTOR)
Acceleration occurs due to a change in the



magnitude of the velocity only,
direction of the velocity only, or
magnitude and direction of the velocity.
Time: seconds (SCALAR)
Note that when an object is thrown vertically upwards, its velocity decreases until it reaches zero at
its maximum height; therefore, and based on what was stated above, velocity and acceleration
must have different signs. Thus velocity is positive and acceleration (due to gravity) is negative.
Similarly, if a particle falls freely, it gains velocity so both velocity and acceleration must have the
same sign, a positive sign.


Scalars are quantities that are fully
described by a magnitude (or numerical
value) alone.
Vectors are quantities that are fully
described by both a magnitude and a
direction.
NEWTON’S LAWS OF MOTION
EARLY BELIEF…
Objects have tendency to stop. If you want to keep them moving, apply force.
ISAAC NEWTON, RENE DESCARTES, GALILEO GALILEI
STATE OF MOTION
1. At rest
2. In motion
FIRST LAW OF MOTION
Every object in a state of uniform motion tends to remain in that state of motion unless an external force is
applied to it.
INERTIA


a tendency to do nothing or to remain unchanged
the property of matter to resist change in its current state
FREE-BODY DIAGRAM
It is a representation of an object with all the forces acting on it.
TYPES OF FORCES ACTING ON AN OBJECT
1.
2.
3.
4.
5.
Normal Force
Weight
Friction
Tension
Applied force
SAMPLES
1. A box is pushed up an incline with friction which makes
an angle of 20° with the horizontal. Let's draw the free-body diagram of the box.
2. A mass hangs from a rope attached to the ceiling.
3. Suppose that you are pushing a crate of mass m over a horizontal frictionless plane.
SECOND LAW OF MOTION
“The force acting on an object is equal to the mass of that object times its acceleration.”
F = ma
THIRD LAW OF MOTION
For every action there is an equaland opposite reaction.