# GUN So I couldn't figure this problem on my physics final. Help?

Discussion in 'On Topic' started by xpinchx, Dec 14, 2007.

1. ### xpinchxhes got a nice cock, on the thin side but its stil

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It was tied in with some kinematics stuff but I couldn't figure it out for the life of me.

Info given:
Mass of a train (kg)
Speed of train (km/h, convert to m/s)
Brake is applied with a force (given in N)
Brake is applied for time (s)

Find the final velocity after braking for t seconds.

It was literally the first question on the test. I tried almost everything I could think of. The first (and most logical) thing I tried was taking the force of the brakes and dividing by the mass of the train to get the acceleration, then just plugging that into a kinemeatics equation, Vx=Vox + a*t, but that didn't get me anything close to any of the multiple choice answers.

Any ideas?

Last edited: Dec 14, 2007
2. ### MTechNew Member

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WTF does this have to do with WMD?

3. ### xpinchxhes got a nice cock, on the thin side but its stil

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4. ### xpinchxhes got a nice cock, on the thin side but its stil

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Well, I was going to delete it but I think I might leave it since it obviously upset you so much.

5. ### mattsb2000OT Supporter

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6. ### MTechNew Member

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03 w/ 33k posts should know better..

7. ### mattsb2000OT Supporter

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9. ### xpinchxhes got a nice cock, on the thin side but its stil

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:07: should know better.

10. ### PanzerAceActive Member

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it stops when it hits the bottom after falling off the bridge that was blown the fuck up

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12. ### 2L Bunny"It's only a Rabbit"

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Fuck, I read your post and starting thinking of equations and started making a FBD in my head. Damn...I'm an engineer....

13. ### SNDPNew Member

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plug all of the answers into the equation until one works out. I love algebra or physics tests with multiple choice answers. ONE of the answers is right, plug them in until one works!

14. ### ClingmanClingman runs Bartertown.

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You have enough there to find v(t), velocity at any time. You were given the total time it takes to stop the train. The integral of velocity will give your displacement. You need to integrate v(t) from time 0 to time t.

15. ### ClingmanClingman runs Bartertown.

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Don't say gun crew never did anything for you

16. ### KeeshActive Member

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There is an elephant in the way.

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18. ### xpinchxhes got a nice cock, on the thin side but its stil

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I never really thought to apply calculus to physics. I'm in algebra-based so they never really showed us how to apply calculus to what we're learning. At least not in a straight-forward manner.

19. ### [DWI]Master of Nothing

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The Ice Cream is melting.

20. ### WaveCarlos Spicy Weiner

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I must be missing something... what exactly are you looking for. I don't see the question, just a bunch of info.

21. ### xpinchxhes got a nice cock, on the thin side but its stil

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lol, the final speed after braking for t seconds. My bad.

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23. ### XR250rdrOT Supporter

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F=ma <- F is brake force, m is train mass. Solve for a

v(t) = vo + at <-substitute in initial velocity (vo), acceleration (a) (remember its negative), and braking time (t).

24. ### XR250rdrOT Supporter

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If they arent teaching it to you, dont worry about it now. You wont need calc to do any of the problems just yet.

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