Question

a bullet strikes a plank of thickness 5cm with velocity 1000m/s and emerges out with velocity of 400m/s. Calculate the average retardation of bullet.

Answer 1

a bullet strikes a plank of thickness 5cm with velocity 1000m/s and emerges out with velocity of 400m/s. Calculate the average retardation of bullet.

Acceleration is defined as the rate of change of velocity with respect to time, in a given direction. If we write the definition for acceleration in mathematical terms we obtain:

$$a = \frac {v - u}{t}$$

$v$ – initial velocity, $u$ – final velocity.

Distance equals:

$$s = \frac {v + u}{2} t$$

If we now combine the two equations that we have derived, we can create another equation:

$$s = \frac {v ^ {2} - u ^ {2}}{2 a}$$

Therefore, retardation of bullet equals:

$$a = \frac {v ^ {2} - u ^ {2}}{2 s} = \frac {1000^{2} - 400^{2}}{2 * 0.05} = 8400000 \frac {m}{s^{2}}$$

Answer: 8400000 $\frac{m}{s^2}$