A 5.0 kg rifle fires a 25 g bullet at 360 m/s.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A rifle fires a bullet at .
- How fast does the rifle recoil if free to move?
- A shooter holds it tight, so they move together. What is the recoil now?
Need a reminder? The key ideaShow
With no outside force, the total momentum of a group of objects stays the same: . Give opposite directions opposite signs. Things that start at rest end with equal and opposite momenta.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Bullet's momentum. .
Step 2. (a) backwards.
Step 3. (b) .
Answer: ; . Holding it tight makes the kick gentle.
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