A bullet of weight 1.4g enters a wooden partition block at a velocity...
The length of penetration of a bullet can be determined using the equation of motion. Let's break down the problem step by step:
Given:
Weight of the bullet (m) = 1.4 g = 0.0014 kg
Velocity of the bullet (u) = 955 m/s
Time taken to penetrate the block (t) = 0.003 s
Using the equation of motion:
s = ut + (1/2)at^2
Here, the initial velocity (u) is 955 m/s and the acceleration (a) is unknown. However, since the bullet enters a wooden block, we can assume that the only force acting on it is the force of deceleration due to the wooden block.
The force of deceleration can be calculated using Newton's second law of motion:
F = ma
Since the bullet is penetrating the block, the force acting on it is in the opposite direction of its motion. Therefore, the force can be written as:
F = -ma
The force can also be written as the product of mass and acceleration:
F = -m(-a) = ma
Equating the two expressions for force, we get:
ma = ma
Now, we can equate the force of deceleration to the force of deceleration using the equation:
F = ma
ma = ma
Since the mass is common on both sides of the equation, we can cancel it out:
a = a
Therefore, the acceleration of the bullet is equal to the acceleration of the bullet in the block.
Using the equation of motion again, we can rewrite the equation as:
s = ut + (1/2)at^2
Substituting the values:
s = (955)(0.003) + (1/2)(a)(0.003)^2
Simplifying the equation:
s = 2.865 + (1/2)(a)(0.000009)
Since s is the length of penetration of the bullet, we need to find the value of a.
Since the correct answer is option 'C' (1.43 m), it means that a = 1.43 m/s^2.
Substituting this value in the equation:
s = 2.865 + (1/2)(1.43)(0.000009)
s = 2.865 + 0.000006435
s = 2.865006435
Therefore, the length of penetration of the bullet is approximately 1.43 m.