PHYSICS!!! help

[scotty_premed]

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alright, i got " most " of the homework done but i am struggling bad with "elastic and inelastic collisions" How do I solve for 2 unknowns? It never works out. Heres the problem. ( A .450 kg ice puck, moving east with a speed of 3.00 m/s has a head on collision with a .900kg puck initially at rest. What will be the speed and direction of each object after collision? ) ANY help or advice is greatly appreciated.

-Scott

 

[DrChandy]

alright, i got " most " of the homework done but i am struggling bad with "elastic and inelastic collisions" How do I solve for 2 unknowns? It never works out. Heres the problem. ( A .450 kg ice puck, moving east with a speed of 3.00 m/s has a head on collision with a .900kg puck initially at rest. What will be the speed and direction of each object after collision? ) ANY help or advice is greatly appreciated.

-Scott

For inelastic collisions:
m1V1+m2V2=(m1+m2)Vf


[.5kg(-3m/s)]+[.9kg(0m/s)]=[1.4kg(Vf)]

Solve for Vf
to get -1m/s

You can solve the above problem in the context of an elastic collision only if you are provided with one of the final velocities.

 

[blaze1306]

Is there a comprehensive book for physics that can help me? My physics instructor, while very cool, is a astronomy geek and knows every formula by heart backwards and forwards. He negelcts to realize that some of us non-trads have not looked a physics problem since highschool 10 years ago, and would not know how to manipulate certain formulas to make it work anyway. Any info an a helpful guide would be appreciated.

 

[BradenDO]

Hmm...I don't know if I did it right but I got Vf2 to be 2m/s and Vf1 to be 1m/s. All I know is that when you have two unknowns you have to substitute, so you would do something like: Vf1=Vf2-3m/s and plug that into Vf1. You then solve for Vf2 get your answer, and you will have one unknown, which is then easily found.

 

[BradenDO]

Is there a comprehensive book for physics that can help me? My physics instructor, while very cool, is a astronomy geek and knows every formula by heart backwards and forwards. He negelcts to realize that some of us non-trads have not looked a physics problem since highschool 10 years ago, and would not know how to manipulate certain formulas to make it work anyway. Any info an a helpful guide would be appreciated.

My physics teacher from high school recommended a book called "The Physics Problem Solver". It really helps. I scored 15pts higher on my last test after reading through it. 🙂