1.

A bullet fired into a fixed target loses half of its velocity after penetrating 3cm. How much further it will penetrate before coming to rest assuming that it faces constant resistance to motion?A. (a) 2.0cmB. (b) 3.0cmC. (c) 1.0cmD. (d) 1.5cm

Answer» Correct Answer - C
Let K be the initial kinetic energy and F be the resistive force. Then according to work-energy theorem,
`W=DeltaK`
i.e., `3F=1/2mv^2-1/2m(v/2)^2` …(1)
For B to C:
`Fx=1/2m(v/2)^2-1/2m(0)^2` …(2)
Dividing eqns. (1) and (2) we get `x/3=1/3`
or `x=1cm`


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