Question

A bullet travelling at a speed of 150 m/s is just able to pierce a plank of 4cm thick. What should be the velocity of the bullet so that it is just able to pierce a plank of thickness 16cm?

Answer 1

Answer:

v= 300 m/sec

Step by step explanation:

It is given that the bullet travels 4 cm at a velocity of 150 m/s.

First of all, we calculate the Energy of the bullet as follows:

$E=\frac{1}{2}mv^2\\ \\E=\frac{1}{2}m(150)^2\\ \\E=11250m$.

We need to calculate the speed if the bullet will travel 16 cm. Therefore, it will have an energy of 16/4 of the original energy.

$E=\frac{16}{4}*11250m=45*10^3m\\ \\45*10^3m=\frac{1}{2}mv^2\\ \\ v^2=90*10^3\\v=300\:m/sec$

Answer 2

Explanation:

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