Question

Пуля, летящая со скоростью 400 м/с, влетела в деревянную доску и углубилась в лес на 20 см. С каким ускорением двигалась пуля внутри доски? На какой глубине скорость пули уменьшилась в 2 раза?

Answer 1

Дано:                           СИ                        Решение

v0 = 400 м/c                                              

V = 0                                                         S= (V^2 - v0^2) / 2a

S = 20 см                      0,2 м                    a = ( (V^2 - v0^2)/ S ) / 2

______________                                       a = ( ( 0 - 160000 м/c)/ 0.2 м ) / 2

a - ?                                                         а = -400000 м/c^2

S-?; V = 200 м/c                                        _______________________

                                   

                                                               S = (-40000 м/c) / -800000 м/c^2

                                                               S = 0.05 м

Answer 2

Calculation of Bullet's Acceleration Inside the Wooden Board

To calculate the acceleration of the bullet inside the wooden board, we can use the equation of motion:

v^2 = u^2 + 2as

where: - v is the final velocity of the bullet inside the board (which is 0 m/s since it comes to a stop) - u is the initial velocity of the bullet (which is 400 m/s) - a is the acceleration of the bullet inside the board - s is the distance traveled by the bullet inside the board (which is 20 cm or 0.2 m)

Rearranging the equation, we get:

a = (v^2 - u^2) / (2s)

Substituting the given values into the equation, we can calculate the acceleration:

a = (0^2 - 400^2) / (2 * 0.2)

Calculating this expression, we find that the acceleration of the bullet inside the wooden board is approximately -800,000 m/s^2.

Depth at which the Bullet's Velocity Decreases by Half

To find the depth at which the bullet's velocity decreases by half, we can use the equation of motion:

v^2 = u^2 + 2as

where: - v is the final velocity of the bullet at a certain depth - u is the initial velocity of the bullet (which is 400 m/s) - a is the acceleration of the bullet inside the board (which we calculated as -800,000 m/s^2) - s is the distance traveled by the bullet inside the board (which we want to find)

We know that the final velocity decreases to half of the initial velocity, so v = 200 m/s.

Rearranging the equation, we get:

s = (v^2 - u^2) / (2a)

Substituting the given values into the equation, we can calculate the depth at which the velocity decreases by half:

s = (200^2 - 400^2) / (2 * -800,000)

Calculating this expression, we find that the depth at which the bullet's velocity decreases by half is approximately 0.1 meters.

Please note that these calculations assume a uniform deceleration of the bullet inside the wooden board. In reality, the deceleration may vary depending on various factors such as the density and composition of the wood.