Page 97 - text book form physics kssm 2020

Chapter 3
Gravitation
Can a satellite orbit the Earth without being driven by a rocket engine? Th e possibility of
th
such movement was predicted by Isaac Newton in the 17 century as shown in Figure 3.18.

Object launched from P with linear speed, v
P
Object launched with low linear
speed will follow trajectory ➊ and
➊ reaches the Earth at Q.
➋
Q Q Q Q
Object launched with suffi ciently
high linear speed will follow
trajectory ➋ circulating the Earth.
Th e object will not return to
the Earth.

Simulation of prediction of
Isaac Newton
Trajectory for free
Earth falling object
circulating the Earth
http://bt.sasbadi.com/p4091b
Figure 3.18 Prediction of Isaac Newton

INTEGRATION OF
Th e prediction of Newton is now a reality with so HISTORY
many man-made satellites orbiting around the Earth without
being driven by any thrust. Satellites always experience Although Isaac Newton did
gravitational force acting towards the centre of the Earth. not have the facilities to carry
out simulation or experiment,
Th e gravitational force on satellites acts as centripetal force.
he was able to visualise the
experiment on the movement
of bodies around the Earth.
His original sketch is
By comparing the formula for force, F = ma shown below.
mv 2
and formula for centripetal force, F = , we obtain:
r
v 2
Centripetal acceleration, a = ,
r
where v = linear speed of satellite
r = radius of the orbit of satellite

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3.1.5