• Support PF! Buy your school textbooks, materials and every day products Here!

Gun shot question

  • Thread starter madahmad1
  • Start date
  • #1
42
0

Homework Statement


A rifle is held rigidly by a supporting test frame. When fired horizontallly, a 50 g bullet attains a muzzle exit velocity of 500 m/s if it takes 0.003 s for the bullet to travel the length of the barrel, determine the average horizontal force applied to the gun by the test frame during firing.



Homework Equations





The Attempt at a Solution



I know that the answer is 8.33 kN but I do not know how to solve it.
I think that we evaluate the forces on the x axis, there are no forces on the y axis but
i am not sure, any help?
 

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
25,832
249
I know that the answer is 8.33 kN
Hint: 8330 is half of 50/.003.
 
  • #3
42
0
lol, so i multiply 50/0.3 by a half? Thanks for the help but can you tell me what steps i should take, i really do not get this problem.
 
  • #4
192
0
F = ma

With what you're given, how can you find the acceleration?

You have the mass, but you have to change it's units so you can get the force in newtons (N).
 
  • #5
tiny-tim
Science Advisor
Homework Helper
25,832
249
(i must admit i think it's a badly-worded question, and i don't really understand the mechanical set-up :frown: … but what they obviously want is …)

ok … Newton's second law …
force = mass times acceleration​
so …
average force = mass times average acceleration …​

and average acceleration is … ? :smile:
 
  • #6
42
0
In order to find the average force we need to know the average acceleration,to find the average acceleration we divide 500/0.003, which is velocity divided by time. This comes out to be 166666.667., then we multuply by 50, correct? I`m sorry if i am wrong but I am really trying to answer this based on the help you are giving me, do we find average acceleration by a different method?
 
  • #7
tiny-tim
Science Advisor
Homework Helper
25,832
249
In order to find the average force we need to know the average acceleration,to find the average acceleration we divide 500/0.003, which is velocity divided by time. This comes out to be 166666.667., then we multuply by 50, correct?
No … 1 N = 1 kg m /s² … so we multiply by 0.05. :smile:
 

Related Threads for: Gun shot question

  • Last Post
Replies
3
Views
3K
  • Last Post
Replies
0
Views
1K
Replies
2
Views
3K
Replies
1
Views
5K
Replies
1
Views
2K
Replies
2
Views
1K
Replies
8
Views
863
Top