1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Gun problem

  1. Jul 8, 2004 #1
    A 0.015 lb. bullet leaves the 23 in. barrel of a 0.30 caliber rifle (whose bore diameter is 0.30 in) at 2000 ft/s. Find the average pressure of the gases in the rifle barrel while the bullet is being accelerated.
     
  2. jcsd
  3. Jul 8, 2004 #2

    AKG

    User Avatar
    Science Advisor
    Homework Helper

    Given distance, initial velocity, and final velocity, calculate acceleration. Use acceleration and mass to calculate force. Use force and the area of the back of the bullet to calculate pressure. You can figure out how to deal with the ugly units.

    [tex]P_{avg} = \frac{(0.015\ lb.)\left (\frac{4,000,000\ ft^2/s^2}{46\ in.} \right )}{\pi (0.15\ in.)^2}[/tex]
     
  4. Jul 8, 2004 #3

    I don't get where you got the 4,000,000 from or the 46 inches.
     
  5. Jul 8, 2004 #4

    AKG

    User Avatar
    Science Advisor
    Homework Helper

    4,000,000 = 2,000² = v² (where v is the final velocity)
    46 = 2 x 23 = 2d (where d is the distance travelled)
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?