# Number of collisions by a bullet

• NODARman
In summary, the problem is trying to find the collision number of a moving bullet hitting wooden blocks, where each collision takes away 10% of the bullet's speed. The question is asking which block the bullet will stay in after exiting the first block, where it loses 10% of its initial speed. The formula Vn=Vn-1-(Vn-1/10) is not applicable in this scenario, as it assumes a decrease in speed after each block, rather than a fixed percentage loss. The correct method involves considering the cause of the speed loss, which can be determined using Newton's second law.
NODARman
New poster has been reminded to always show their work when starting schoolwork threads.
Homework Statement
I'm trying to calculate collision number.
Relevant Equations
.
How to find the collision number if the moving bullet hits a few wooden blocks and every collision takes 10 percent of its speed. In which block will the bullet stay?

NODARman said:
Homework Statement:: I'm trying to calculate collision number.
Relevant Equations:: .

How to find the collision number if the moving bullet hits a few wooden blocks and every collision takes 10 percent of its speed. In which block will the bullet stay?
Why would a wooden block reduce a projectile's spped by a fixed percentage? Would something hitting the block at ##1 \ m/s## emerge at ##0.9 \ m/s##?

IDK. That physics task in the book says that the speed of a bullet decreases by 10% after hitting every block. Every block has the same length. The task doesn't contain L, V, or K. There is only a 10% of speed loss. I've just written the formula:
Vn=Vn-1-(Vn-1/10)
I think this formula works in general, but I don't need it here.

NODARman said:
IDK. That physics task in the book says that the speed of a bullet decreases by 10% after hitting every block. Every block has the same length. The task doesn't contain L, V, or K. There is only a 10% of speed loss. I've just written the formula:
Vn=Vn-1-(Vn-1/10)
I think this formula works in general, but I don't need it here.
That might take a lot of blocks! Are you sure the book doesn't say that it loses 10% of its speed going through the first block? Not every block?

Yeah, yeah, the first block. I forgot to say that because I don't really understand what it means (and also how to solve it).
Thanks.

NODARman said:
Yeah, yeah, the first block. I forgot to say that because I don't really understand what it means (and also how to solve it).
Thanks.
What do you think might be the constant factor in each collision?

"The bullet is hitting a few wooden blocks which are placed at a different distance from each other. In which block will the bullet stick if after exiting the first block, it loses 10% of its initial speed."
(I've translated as I could)

So, if after the fist hit the bullet lost 10% of its initial speed, it means the V1=V0-(V0/10) (this will be the second speed of the bullet which will hit the second block). Is that mean that every hit reduces the speed by 10% of V0 and not Vn=Vn-1-(Vn-1/10).

If we put the numbers in the first case, then the speed would be, let's say: 100, 90, 80, 70, etc.
The second case: 100, 90, 81, 78, etc.

NODARman said:
"The bullet is hitting a few wooden blocks which are placed at a different distance from each other. In which block will the bullet stick if after exiting the first block, it loses 10% of its initial speed."
(I've translated as I could)

So, if after the fist hit the bullet lost 10% of its initial speed, it means the V1=V0-(V0/10) (this will be the second speed of the bullet which will hit the second block). Is that mean that every hit reduces the speed by 10% of V0 and not Vn=Vn-(Vn/10).

If we put the numbers in the first case, then the speed would be, let's say: 100, 90, 80, 70, etc.
The second case: 100, 90, 81, 78, etc.
This is not the correct method. You must consider why it loses speed. What causes the bullet to lose speed? Hint Newton's second law.

NODARman

## 1. What factors affect the number of collisions by a bullet?

The number of collisions by a bullet can be affected by several factors, including the velocity of the bullet, the density and composition of the material it is colliding with, and the angle at which it strikes the material.

## 2. How does the velocity of the bullet impact the number of collisions?

The velocity of the bullet plays a significant role in determining the number of collisions it will make. A higher velocity means the bullet will be able to travel further and potentially collide with more objects before losing its energy.

## 3. Does the density of the material affect the number of collisions?

Yes, the density of the material can impact the number of collisions by a bullet. A denser material will slow down the bullet more quickly and potentially cause it to collide with more objects before coming to a complete stop.

## 4. Can the angle of impact affect the number of collisions?

Yes, the angle at which the bullet strikes a material can impact the number of collisions. A more direct impact will result in more collisions, while a glancing impact may cause the bullet to ricochet off and have fewer collisions.

## 5. How can the number of collisions by a bullet be calculated?

The number of collisions by a bullet can be calculated by considering the velocity of the bullet, the density and composition of the material it is colliding with, and the angle of impact. This calculation can be complex and may require advanced mathematical models or simulations.

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