Kinematic Equation: Accel of Bullet Through 8.1cm Thick Board

  • Thread starter krazykaci
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In summary, a bullet with a speed of 452 m/s is fired through a board that is 8.1 cm thick and emerges with a speed of 298 m/s. Using the formula v^2=v0^2+2a(x-x0), with x0=0 and x=8.1 cm, the average acceleration of the bullet through the board is calculated to be approximately -7129.63 m/s^2. However, this answer may be incorrect due to inconsistent units or other factors.
  • #1
krazykaci
28
0
another one!

An indestructible bullet 1.86cm long is fired straight through a board that is 8.1cm thick. the bullet strikes the board with a speed of 452 m/s and emerges with a speed of 298 m/s. what is the average acceleration of the bullet through the board? answer in units of m/s^2

what would the length of the bullet and the width of the wall be used for in a kinematic equation? I know 452=v. and 298=v ... or is that wrong?
 
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  • #2
Use the same formula for acceleration as your tennis ball question.
 
  • #3
Think. You have to find the acceleration. List the things you know. Then look at your equations again. List all things that are relavant to kinematics.
 
  • #4
what would the time variable be then?
 
  • #5
If you don't know it label it as just t=?. But look at your equations, they all don't have something in it. Each one doesn't have one of these a,v,t,d so which oe should you use.
 
  • #6
v=v.+a(t)

i know v=452m/s
v.=298 m/s
a= unknown
but i don't know what t should be, and it is known isn't it?
 
  • #7
Do you need time?
Your missing a variable, distance.
There are other equations you can use.
 
  • #8
oh, so I am using v^2=v.^2+2a(x-x.)? right?
 
  • #9
Yes, List out everything you know before you even start a problem. This will help with some headaches. Look for what you don't know also and choose your equation with this information.
 
  • #10
so do I use 8.1 and 1.86 to find displacement?
 
  • #11
The bullet is only deaccelerated over 8.1cm. The width of the board.
 
  • #12
can you explain it in a different way. I don't understand how that fits into the equation.
 
  • #13
Your initial x=0 because the bullet has not been acted upon yet so your final x=8.1cm
 
  • #14
ok so the equation is 298^2=452^2+2a(8.1-0) right?
 
  • #15
looks good to me!
 
  • #16
the answer I am getting (-7129.63) is apparently incorrect. can you work it out and see if I am just doing my math wrong?
 
  • #17
whats the right answer?
 
  • #18
i don't know! i am doing the equation and I am getting that answer, but the computer is saying it is the wrong answer!
 
  • #19
well I'm getting a different answer than you also. Check your units. Stay consistent.
 

Related to Kinematic Equation: Accel of Bullet Through 8.1cm Thick Board

1. What is the kinematic equation for the acceleration of a bullet through an 8.1cm thick board?

The kinematic equation for this scenario is a = (v^2 - u^2) / 2d, where a is the acceleration, v is the final velocity, u is the initial velocity, and d is the distance traveled.

2. Is the acceleration of a bullet through an 8.1cm thick board constant?

No, the acceleration of the bullet is not constant. It will experience a deceleration as it passes through the board due to the resistance and friction of the material.

3. How does the thickness of the board affect the acceleration of the bullet?

The thicker the board, the greater the distance the bullet has to travel and the longer it will take to decelerate. This means that the acceleration will be lower for a thicker board compared to a thinner one.

4. Can the kinematic equation be used to calculate the acceleration of a bullet through different materials?

Yes, the kinematic equation can be used to calculate the acceleration of a bullet through different materials as long as the variables of initial and final velocity and distance traveled are known.

5. Are there any other factors that may affect the acceleration of a bullet through a board?

Yes, there are other factors that may affect the acceleration of a bullet through a board, such as the shape and density of the bullet, the angle at which it enters the board, and the type of material the board is made of.

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