Tricky Friction and Momentum Questions. Help Appreciated

[jambition]

Alright, last time I made a post I got some great help from the people who contributed. Again, I'm not interested in answers but a guided discussion on processes would be extremely helpful! I'm so close to completing these equations but I just need a push in the right direction. Please help a physics student out!

4a. A 30-06 caliber hunting rifle fires a bullet of mass 0.00976 kg with a velocity of 421 m/s to the right. The rifle has a mass of 2.95 kg.
Recoil speed of rifle is 1.39287 m/s.

If the rifle is stopped by the hunter’s shoulder
in a distance of 2.14 cm, what is the magnitude of the average force exerted on the shoulder by the rifle?
Answer in units of N

4b. Is this another kinetics equation? I'm looking for force but there's distance involved so does that mean I have to find velocity?

4c. It's simple but for some reason I cannot seem to know where to start. Any suggestions?

 

[Delphi51]

Yikes, too many questions at once! On the car stopping distance, you should be able to find the force of friction, then use it in F=ma to get the deceleration of the car. Finally, use one or two accelerated motion formulas to find the stopping distance.

 

[jambition]

Just solved two. Still need some help on the last two?

 

[donutz610]

Whenever a variable is not given i try to set up two equations with two unknown variables such as your mass and something else. Then you combine the equations through substitution to find one of your variables. Once you have that variable you can solve for the other one. In your situation it may not work but whenever I am stuck i try that. Give it a shot.

 

[jambition]

Thanks! I just solved it (finally). Now I'm just stuck on the rifle problem.