NCERT Exercise 3.15 An aircraft executes a horizontal loop of radius 1.00 km with a steady speed of 900 km/h. Compare its centripetal acceleration with the acceleration due to gravity.
v = 900 km/h = 250 m/s
Centripetal Acceleration,
ac = v2/r = 2502 /1000 = 62.5 m/s2
g = 9.8 m/s2
ac = 6.4 g (6.4 times the gravitational acceleration)
What is G Force?
We are constantly experiencing a gravitational force with acceleration due to gravity g = 9.8 m/s2. If the car is accelerating by 2 m/s2 we get pushed backwards with the same acceleration called Psuedo acceleration. (Pseudo Force). When the aircraft is accelerating in the runway we experience the same kind of backward push but the magnitude is much higher. The same can be extended to fighter jets and rockets for astronauts where the acceleration they experience can be extremely high say 5 times the gravitational acceleration or 10 times the gravitational acceleration which is famously referred as 5 g force or 10 g force.
Huge centrifuge machines are used in space agencies like ISRO, NASA and other fighter jet pilot training centers were the trainees are put into these machines to see how far they are able to withstand. Most of them pass out (become unconscious) around 4 g or 5 g.
These centrifuge machines are based on the circular motion principles, centripetal acceleration = r w2 ( r omega squared). To increase the acceleration r radius is kept very high and w (omega) angular speed keeps increasing.
From the Handbook
Sustained G-forces of even 6 Gs would be fatal. For example, the car crash that killed Princess Diana of Wales in 1997 was estimated to range somewhere between 70–100 Gs.
ReplyDeleteA quick calculation gives a value of 6.5 times g for normal acceleration.