For a rocket to escape from the earth
all it needs is enough thrust to escape
the gravitational pull to the earth
The rocket generally works on the
principle of NEWTONS laws of motion
we can check how rocket escapes earth's
gravity by considering NEWTONS three
laws of motion
According to the newton's first law of
motion every body continues in a state
of rest unless it is act upon an
external unbalanced force
consider a person holding a ball in his
hand and keeping it still
we can say the ball is at rest the force
of gravity will try to pull the ball
downward while the same time
his hand is pushing against the ball to
hold it up
now forces acting on the ball is
balanced now the person is going to
release the ball from his hand at that
time
forces acting on the ball becomes
unbalanced the ball then changes from
state of rest to state of motion
a rocket also experiences balanced and
unbalanced forces all the time
rocket on the launch pad is balanced the
surface of the pad pushes the rocket up
while gravity tries to pull it down
as the engines are ignited thrust from
the rocket unbalances the forces and the
rocket travels upward
the rocket then changes from state of
rest to state of motion
According to newton's second law of
motion the net force on an object is
equal to the mass of the object
multiplied by the acceleration of the
object or simply we can say force equals
mass times
acceleration consider a cannon is fired
and at the time of explosion the
cannonball propels out the open end of
the barrel
it flies a kilometer or two and hits its
target
at the same time canon itself push
backward a meter or two
we can represent this event on the basis
of NEWTONS second law of motion
Let capital F equals mass cannon times
acceleration of cannon
small f equals mass of the ball times
acceleration of ball
this capital Fand small f are created
by exploding gun powder
so we can write capital F equals smaller f
that is mass of the cannon times
acceleration of the cannon equals the
mass of the ball times acceleration of
the ball. In order to make this equation
equal the acceleration vary with mass
cannon has large mass and small
acceleration and the cannon ball has
small mass and large acceleration
let's supply this principle to our
rocket .Replace the mass of the
cannon ball with the mass of the gas been
ejected out of the rocket engine
replace the massive cannon with the mass
of the rocket moving in other direction
force is the pressure created by the
control explosion taking place inside
the rocket engines
that pressure accelerates the gas in one
way and the rocket the other
next we can check the rocket movement
according to the NEWTONS third law of
motion
the law states that for every action
there is an equal and opposite reaction
A rocket can lift up from a launch pad
only when it expels gas out of its
engine
Rocket pushes on the gas and the gas in
turn pushes on the rocket
the whole process is similar to riding
the skateboard
when a rider jumps off the skateboard
according to the third law the jumping
is called
action the skateboard responds to the
action by traveling some distance
the motion of the skateboard is called
reaction
when the distance traveled by the rider
and the skateboard are compared
it would appear that skateboard has much
greater reaction than the action of the
rider
with rockets the action is expelling of
gas out of the engine
the reaction is the movement of the
rocket in opposite direction
to enable a rocket to lift up from the
launch pad the action or the thrust from
the engine must be greater than the mass
of the rocket
hope you all understood how a rocket
work on the basis of
NEWTONS laws of motion if you have any
doubts
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