.Calculating Time for .22 Rifle Bullet to Stop in Soft Wood

  • Thread starter Thread starter theonerealazn
  • Start date Start date
  • Tags Tags
    Bullet Time Wood
AI Thread Summary
To calculate the time required for a .22 rifle bullet to stop in soft wood, the bullet's initial velocity is 350 m/s, and it penetrates 0.130 m. The retarding force exerted by the wood is 848 N, derived from the bullet's mass of 1.80 g. Using the equation Vf = Vi + a*t, where the final velocity (Vf) is 0, the initial velocity (Vi) is 350 m/s, and acceleration (a) can be calculated from the force and mass. The initial calculation of time was incorrect due to a factor of 2 error. The correct approach involves accurately determining the acceleration and then solving for time using the kinematic equations.
theonerealazn
Messages
1
Reaction score
0
Ok, so here's my question:

A .22 rifle bullet, traveling at 350 m/s, strikes a block of soft wood, which it penetrates to a depth of 0.130 m. The block of wood is clamped in place and doesn't move. The mass of the bullet is 1.80 g. Assume a constant retarding force.

I know this has already been posted in another thread, but i have an additional question that i can't get.
1. How much time is required for the bullet to stop?
i tried 0.130m/350m/s and got .00037143 seconds as an answer. This was not correct. Any suggestions on what to do?

I already know that the wood exerts 848 N on the bullet
 
Physics news on Phys.org
F=ma where F=net force on the bullet=848N and m=mass of the bullet=.0018kg. Find a

Vf=Vi+a*t
Vf, Vi and a are all known at this point. Solve for time.

Your answer is close. You are off by a factor of 2.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top