## anonymous one year ago Is tension force equivalent to applied force?

1. anonymous

So let's say there is a tension force of 360N acting on a 30kg object on a flat surface with no friction. Acceleration can be calculated using the newton's second law F=ma such that 360N=30kg(a) a=12/s^2

2. anonymous

@IrishBoy123

3. IrishBoy123

if the object is being pulled by a rope, then the force on the object and the tension in the rope are one and the same, yes with our usual assumption that the rope is massless

4. anonymous

The rope is indeed not very massless but I hope physicists are smart enough to account for everything elseXD

5. anonymous

we assume the rope is massless so the problem will be easier

6. Loser66

Question: Where is gravity?

7. anonymous

i forget why it is easier to assume rope is massless

8. IrishBoy123

flat surface and frictionless

9. Loser66

The problem indicates to tension and friction, but gravity is there still.

10. IrishBoy123

ah, yes, but it is acting orthogonal to motion so indeed you would have R = mg in the up down direction equalling zero

11. Loser66

|dw:1439468269722:dw|

12. IrishBoy123

if the rope is not massless then the tension is greater the further away from the block you are pulling because that part of the rope is pulling the block and the rest of the rope in addition you will have a force downwards on the rope - gravity

13. Loser66

Because no friction, so that the box moves with constant velocity and total force is as shown.

14. Loser66

Actually, I don't know, hehehe... I forgot all of my physics knowledge. @IrishBoy123 rely on you. :)

15. IrishBoy123

|dw:1439468440385:dw|

16. IrishBoy123

@Loser66 if you are ever relying on me, you are in such trouble :-)) lol!!

17. anonymous

@IrishBoy123 so my answer turns out wrong.

18. anonymous

I seem to have neglected the gravity... He says this

19. anonymous

Fnet = ma Ft – Fg = ma 360 – m g = m a 360 – 30 x9.8 = 30 a a= 2.2 or 2 m/s2 upward

20. anonymous

So the unbalanced force was 360 N as you all know it, Mass of the object being moved was 120kg gravity is 9.8m/s^2 Surface is frictionless Force of tension=360N which @IrishBoy123 had claimed as being equivalent to applied force to the object with a mass of 120kg

21. IrishBoy123

not sure which we are now discussing can you draw it?

22. anonymous

|dw:1439472031159:dw|

23. anonymous

Sorry basically 30kg object being applied 360N tension force acceleration of which is being looked for.

24. IrishBoy123

|dw:1439472054470:dw|

25. anonymous

Yes.

26. anonymous

But this is wrong ?

27. IrishBoy123

cool. here the surface is horizontal and frictionless, so we don't have to worry about gravity

28. IrishBoy123

if the drawing is accurate, the solution is correct can you post the question or link it?

29. anonymous

You have neglected gravity which acts downward.

30. anonymous

Fnet = ma Ft – Fg = ma 360 – m g = m a 360 – 30 x9.8 = 30 a a= 2.2 or 2 m/s2 upward

31. anonymous

*quoted from my teacher.

32. anonymous

|dw:1439472226663:dw|this is tensile force which is also applied force

33. anonymous

means the object is being pulled

34. IrishBoy123

ok there is a context here which i am clearly missing i think you have this |dw:1439472256031:dw|

35. IrishBoy123

but you mentioned a flat surface with no friction. that was the source of the confusion |dw:1439472446011:dw|

36. anonymous

this force whether its tension or not is pretty irrelevant unless you are calculating deformation/stress/strain

37. IrishBoy123

until we see the actual question or a good drawing, we are just guessing ..... and i am no good at that :p

38. anonymous

"A mass of 30 kg is hauled upward by a rope. The tension in the rope is 360 N. What is the magnitude of the acceleration of the mass?"

39. anonymous

Sorry it was my faulty @IrishBoy123

40. anonymous

I guess I was mixed up with some other questions which posed "frictionless surface"

41. IrishBoy123

no worries ;-)