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

Finding recoil velocity only given force and firing velocity

  • Thread starter junkmonk
  • Start date
1. Homework Statement
A 50.0N bullet leaves a 40.0N gun with a velocity of 200. m/s. What is the recoil velocity of the gun?


2. Homework Equations
I tried to figure this out by using anything in relation to FΔt = mΔv but, I'm left with two unsolved variables, Δt and m...
 
2,013
482
Draw a FBD for the gun and for the bullet and then write eqn of motion for each one (or impulse--momentum relations for each one).
 
Okay, well I can write out the impulse relations on the FBD. Since FΔt=mΔv, then F=mΔv/Δt.
SO, putting m1Δv1/Δt = m2Δv2/Δt still leaves me with the mass unavailable, they don't cancel out since they're different... How do I solve this without the mass (or time)?

I'm just getting into impulse, the only impulse equation I've learned thus far IS FΔt=mΔv, so if there's any way that it can be solved using that or that with any other combination of simple linear motion equations, it would be best understood. But if there's no other way, than I'll definately attempt to learn.

Thanks.
 
2,013
482
This is all happening some where close to the surface of the earth, I presume? You were given weights, so masses should not be too difficult to find. Pretty strange weight values, however; that is one heavy bullet!

You need to think a bit about what velocity you are given.
 

Related Threads for: Finding recoil velocity only given force and firing velocity

Replies
13
Views
23K
Replies
1
Views
1K
  • Posted
Replies
15
Views
38K
Replies
2
Views
2K
Replies
9
Views
20K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top