Question

) A bullet of mass 30 g and moving with velocity u, hits a wooden

target with a force of 150 N. if the bullet penetrates 100 cm in the

target, what is the magnitude of u?​

Answer 1

Given:

A bullet of mass 30 g and moving with velocity u, hits a wooden target with a force of 150 N. if the bullet penetrates 100 cm in the target.

To find:

Value of u ?

Calculation:

First of all, let's find out the acceleration experienced by the bullet after entering the target.

$\therefore \: a = \dfrac{f}{m}$

$\implies \: a = \dfrac{150}{( \frac{30}{1000} )}$

$\implies \: a = 5000 \: m {s}^{ - 2}$

Now, applying 3rd equation of kinematics:

$\therefore \: {v}^{2} = {u}^{2} + 2as$

$\implies \: {(0)}^{2} = {u}^{2} + \bigg \{2 \times ( - 5000) \times \dfrac{100}{100} \bigg \}$

$\implies \: {u}^{2} = 2 \times 5000\times \dfrac{100}{100}$

$\implies \: {u}^{2} = 10000$

$\implies \: u = 100 \: m {s}^{ - 1}$

So, initial velocity of bullet is 100 m/s.