Register to reply 
Constant resisting force 
Share this thread: 
#1
Jan2207, 09:45 PM

P: 4

1. The problem statement, all variables and given/known data
a 500 lb gun fires a 2lb projectile with a muzzle velocity of 1600 ft/s. if the recoil is against a constant resisting force of 400 lb, find the time taken to bring the gun to rest and the distance it recoils. a) .20s, .80ft b) .25 s, .80 ft c) .25 s, .85 ft d) .15 s, .75 ft 2. Relevant equations p=mv 3. The attempt at a solution initial recoil is 6.4 ft/s (500*6.4=2*1600) i'm not sure where to start on this...the constant resisting force means what? i've never come across that before. 


#2
Jan2207, 10:23 PM

Sci Advisor
HW Helper
PF Gold
P: 6,049




#3
Jan2307, 06:21 PM

P: 4

ah. could you show me how you would set about solving it? stepbystep, if you can, because i need to understand how to do this myself.



#4
Jan2307, 07:11 PM

Sci Advisor
HW Helper
PF Gold
P: 6,049

Constant resisting force



#5
Jan2307, 07:29 PM

P: 4

it still does not fully register with me. i'm not sure how to use the impulse formula in this case.
(this isn't right, but here's what i did) 400lb*t=(500lb*6.4ft/s)0 but that gives me a time of 8 seconds i used the vf^2=vi^2+2ad to find that (6.4/t)(d)=20.48 i know that the right answer is b) .25 s, .80 ft already, but i just need to understand how to plug everything in to the impulse equation because it's just not sinking in. 


#6
Jan2307, 10:55 PM

Sci Advisor
HW Helper
PF Gold
P: 6,049

vf =0, and vi = 6.4. 


#7
Jan2407, 06:02 PM

P: 4

400*t=(500/9.8)*6.4
t=.815s, which isn't the correct answer. what else did i mess up? lol. 


#8
Jan2407, 06:55 PM

Sci Advisor
HW Helper
PF Gold
P: 6,049




Register to reply 
Related Discussions  
Constant Force  Introductory Physics Homework  5  
Constant force problem  Introductory Physics Homework  11  
Force and constant velocity  Introductory Physics Homework  3  
Constant force?  Introductory Physics Homework  4  
Defining mass resisting movement exerting energy  General Physics  4 