A whip crack is illustrated below. To crack the whip, it is thrown forward with

Question

A whip crack is illustrated below. To crack the whip, it is thrown forward with a velocity of 10 m/s and the handle is stopped in a vertical position instantly forming a tight loop that propagates forward. The whip is 3m long and has a mass (excluding the handle) of 0.4kg.
(a) Explain why momentum is not conserved in this system.
(b) Explain why energy is conserved in this system.
(c) Assuming the mass of the whip is uniformly distributed along its length, calculate the velocity of the end of the whip as a function of the position of the loop (
x), and calculate the position of the loop as the end of the whip breaks the speed of sound (340m/s).
(d) Explain why whips are usually tapered.

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Explanation / Answer

Momentum is always conserved in isolated system
here system initially isoltaed but after folding of whip system does remain isloated
Energy is conserved in system because here there is no chance of loss of energy by sound, friction or any other factor which we ignore in caalculation.
Whips are tapered to lower the friction against the air because on tapering flow of fluid accross it will obviously remain laminar or in other word smooth.
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