A car driver going at some speed v suddenly finds a wide wall at a distance r.Should he apply brakes or turn the car in a circle of radius r to avoid hitting the wall?

Asked by Biswajit | 17th Dec, 2013, 07:37: PM

Expert Answer:

Let F1 be the braking force, so as to stop the car just in the distance r. 
Then,
work done by the braking force = kinetic energy of the car
or F1 x r = 1/2 mv2
or F1 = (mv2) / 2r                                 ...1
Let F2 be th force required (centripetal force force) for taking a circular turn of raduis r.
Then,
F2 = mv2 / r                                         ...2
From the equations (1) and (2), we have
F1 = 1/2 F2
Since the force needed to apply brakes is just half of the force required to take the circular turn, it is better to apply brakes.

Answered by Faiza Lambe | 27th Jan, 2014, 12:55: PM

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