Page 296 - General Knowledge
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GENERAL KNOWLEDGE 2019
If you are in circular motion, your direction of motion is constantly changing.
This means you are constantly accelerating.
If you are constantly accelerating, there must be a force acting on you the entire time.
The force exerted is the centripetal force and always points toward the center of the circle.
In circular motion the centripetal force is always perpendicular to the motion.
The Third law
For every action there is an equal and opposite reaction.
The statement means that in every interaction, there is a pair of forces acting on the two
interacting objects.
The size of the forces on the first object equals the size of the force on the second object.
The direction of the force on the first object is opposite to the direction of the force on the
second object.
Forces always come in pairs are equal and opposite reaction force pairs.
This is saying that whenever an object exerts a force on another, there will be an equal and
opposite reaction exerted by the second on the first.
Consider a rugby player swerving to the right to avoid a tackle.
For every action (the rugby player pushes the ground to the left with their feet) there is an
equal and opposite reaction (the ground exerts an equal force to the right allowing the player
to swerve in that direction).
A force is a push or pull upon an object.
This implies there must be two objects, one being pushed and one doing the pushing.
Thus, forces from interactions between objects.
According to Newton‘s Third Law, whenever objects interact with each other they exert
forces upon each other.
These two forces the objects on each other are called action and reaction.
Rocket propulsion
The reaction of a rocket is an application of the third law of motion.
Various fuels are burned in the engine, producing hot gases.
The hot gases push against the inside tube of the rocket and escape out the bottom of the
tube.
As the gases move downward, the rocket moves in the opposite direction.
The third law states that all forces between two objects exist in equal magnitude and
opposite direction;
If one object A exerts a force FA on a second object B, then B simultaneously exerts a force
FB on A, and the two forces are equal in magnitude and opposite in direction. .
2. WORK
When a force acts on an object and the object actually moves in the direction of force, then
the work is said to be done by the force.
Work done by the force is equal to the product of the force and the displacement of the
object in the direction of force.
If under a constant force F the object displaced through a distances, then work done by the
force
Where ―a‖ is the smallest angle between F and s.
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