Question

A bullet moving with 10 m/s hits a wooden plank. The bullet stops after penetrating the plank 2 cm deep. Calculate the retardation of the bullet.

Answer 1

Step 1:Given data:

1. Initial velocity of the bullet, u = 10 m/s,
2. Distance traveled by the bullet, s = 2 cm = 0.02 m,
3. Final velocity of the bullet, v = 0 m/s.

Finding acceleration:

Using the equation of motion:

$v^2=u^2+2as$

Where v and u are the final and initial velocities respectively, a is a constant acceleration, and s is the distance traveled.

Substitute the given values in the equation,

${\left(0\right)}^2={\left(10\right)}^2+2a(0.02)$

$$\begin{gathered} -\frac{100}{0.04}=a \\ a=-2500m/s^2. \end{gathered}$$

Now we know that the negative value of acceleration is retardation.

Therefore, the retardation of the bullet is 2500 m/s².