Question

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

Answer 1

M*V0^2/2=F*L
F=m*V0^2/2*L=400^2/2*0,2=4*10^5 м/с2
V^2=V0^2-2*a*S
S=(V0^2-V^2)/2*a=(400^2-200^2)/2*4*10^5=0,15 м

Answer 2

Calculation of Acceleration and Depth

To calculate the acceleration of the bullet inside the wooden board and the depth at which its speed is reduced by half, we can use the following information:

- Initial velocity of the bullet: 400 m/s - Depth of penetration into the wooden board: 20 cm

To find the acceleration, we can use the equation of motion:

v^2 = u^2 + 2as

where: - v is the final velocity (which is 0 m/s when the bullet stops inside the board) - u is the initial velocity (400 m/s) - a is the acceleration - s is the distance traveled (20 cm or 0.2 m)

Rearranging the equation, we have:

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

Substituting the values, we get:

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

Simplifying the equation, we find:

a = -400,000 m/s^2

The negative sign indicates that the bullet experiences deceleration or negative acceleration.

To find the depth at which the bullet's speed is reduced by half, we can use the equation:

v = u + at

where: - v is the final velocity (200 m/s, half of the initial velocity) - u is the initial velocity (400 m/s) - a is the acceleration (-400,000 m/s^2) - t is the time taken to reach the final velocity

Rearranging the equation, we have:

t = (v - u) / a

Substituting the values, we get:

t = (200 - 400) / -400,000

Simplifying the equation, we find:

t = 0.0005 seconds

To find the depth, we can use the equation of motion:

s = ut + (1/2)at^2

where: - s is the distance traveled (depth) - u is the initial velocity (400 m/s) - a is the acceleration (-400,000 m/s^2) - t is the time taken (0.0005 seconds)

Substituting the values, we get:

s = (400 * 0.0005) + (0.5 * -400,000 * (0.0005)^2)

Simplifying the equation, we find:

s = 0.1 meters or 10 cm

Therefore, the bullet's speed is reduced by half at a depth of 10 cm inside the wooden board.

The bullet's acceleration inside the wooden board is approximately -400,000 m/s^2, and the depth at which its speed is reduced by half is 10 cm.