## YumYum247 one year ago Someone help me please!!!!!! :")

1. YumYum247

I need help with question 25, a,b,c

2. YumYum247

What does it mean by "coupling"?!?!??!?!?

3. YumYum247

@peachpi

4. YumYum247

do you want me to upload my work?????? i've tried to do the question but idk if it's even right tho :(

5. YumYum247

@dan815

6. YumYum247

7. YumYum247

8. pooja195

@nincompoop @TheSmartOne

9. pooja195

@Zale101

10. YumYum247

11. YumYum247

12. YumYum247

Thank you peachpi, my throat is all dried up from writing out loud to people for help...:"(

13. YumYum247

and Welsshfella!! :")

14. welshfella

my physics is pretty rusty i'm afraid..

15. anonymous

seriously, I have no confidence in this. It's a wild shot in the dark. I'm thinking for a) you need to account for the mass of all 15 cars and for b) only the last 8|dw:1442519089103:dw|

16. YumYum247

that's what i did....but i'm not too sure either.....and Welfella....Thank you for even attempting to help me. :")

17. welshfella

you use Newton's second law of course F = ma and the third law? which deals with equal and opposite reactions

18. YumYum247

So this is what i did, first i multiplied the total mass of the 15cars = 96000Kg by the acceleration to get the net force of the train pushing on the buggies. (19,200N)

19. welshfella

the coupling is the connection between the engine and the first car and also between all the 15 cars. It will be a rigid bar which will be in tension.

20. welshfella

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21. YumYum247

To find the force on the "coupling" between car number 8 and 9. first i counted how many cars number 8 is from 15 which is 8...i think...i multiplied the mass of all 8 cars by the acceleration and then counted the mass of all the cars from 9 to 15 and multiplied their mass by ht acceleration and subtracted the net force from 8 to 9 to get the net force between cars 8 and 9.

22. welshfella

the above is a simple case with one engine and one car

23. YumYum247

yes @welshfella did you see the resolution of the questions i uploaded?!?!?!?!?

24. welshfella

the tension in the coupling can be found by Newtons 2nd law T = m * a = 6400 * 0.2 = 1280 N

25. welshfella

No i'll take a look

26. YumYum247

true but have you seen how i attempted to do the next question.....

27. YumYum247

alright....

28. welshfella

I'm afraid I cant see it very well with my old eyes!!! lol

29. YumYum247

Aaawwnnn, try to zoom in...:)

30. welshfella

you are on the right track, I believe

31. YumYum247

Ok can you please help me find how far along the track the train must have travelled in 2 minutes after starting??????/

32. YumYum247

the acceleration of the train is 0.20m/sec^2 and the total mass of the train is 96000Kg, and the net force on the buggies with all the load is 19,200N.

33. anonymous

You can use the kinematic formula since acceleration is constant $d=v_0t+\frac{ 1 }{ 2 }at^2$

34. YumYum247

but what is the initial velocity of the train tho :"(

35. anonymous

0, the train is initially at rest

36. YumYum247

oh....the train is motionless....so Vi = om/sec.

37. YumYum247

ok just last question.....did i do questu=ion "B" right????

38. YumYum247

just take a look at the work i've uploaded....

39. anonymous

it looks right

40. YumYum247

41. YumYum247

Ok thank you and i LOVE you!!!! :")

42. anonymous

lol let me know how this turns out.

43. YumYum247

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