Force ( F ) Centrifugal Force (Chistiaan Hygens in
A force is a push or pull upon an object
resulting from the object"s interaction with It is the tendency of an object following a
another object. curved path to fly outwards, away from the
It is a product of mass and acceleration. center of the curve. It is the inertia of motion.
Its unit is newton and represented by the e.g. Mud flying off a tire; children pushed out
symbol F. on a roundabout.
Force = mass x acceleration
or F ma Centripetal Force (Isaac Newton in 1684)
1N = 1 kg x 1m/s2.
The force that keeps an object moving with a
uniform speed along a circular path. e.g.
Satellite orbiting a planet.
NEWTON’S LAWS OF MOTION
Isaac Newton (1643-1727), the physicist who formulated the laws of motion
Newton"s First Law of Motion
It states that every object will remain at Newton"s Second Law of Motion
rest or in uniform motion in a straight line
unless compelled to change its state by the It explains how the velocity of an object
action of an external force. changes when it is subjected to an external
This is normally taken as the definition of force.
inertia. (Galileo"s concept "Law of It defines a force to be equal to change in
Inertia") momentum (mass times velocity) per
The key point here is that if there is no net change in time.
force acting on an object (if all the Newton also developed the calculus of
external forces cancel each other out) then mathematics, and the "changes" expressed
the object will maintain a constant in the second law are most accurately
velocity. If that velocity is zero, then the defined in differential forms. For an object
object remains at rest. If an external force with a constant mass m, the second law
is applied, the velocity will change states that the force (F) is the product of
because of the force. an object"s mass (m) and its acceleration
The first law can be stated mathematically (a):
F 0 dt 0