Ask you all a science question...
-
Excellent answer. This is the correct answer.Originally posted by le cruz:If
Fa = force exerted from side of pendulum
Fb = tension in string
G = gravitational force
@ = angle between vertical datum and string
Fb cos @ = G
Fb sin @ = Fa
Fa = G sin @ / cos @ = G tan @
Plot Fa = G tan @ for @ = 0° to 90°
This question is a standard and simple question from A levels, making use of the knowledge of trigo and resolution of horizontal and vertical forces. -
2nd one thanks for the effort in drawing....Originally posted by blahshit:like that?
or
if it's the 1st 1, i think i have given u the answer.. but if 2nd 1, i not very sure.. think 2nd 1 need to jus potential and kinectic energy thingy...
Thanks for all the standard 10 year series a level answers but anything for a simple guy like me? -
u r welcome.. pai seh and sorry hor.. cannot help u out after so long.. haha..Originally posted by banzie:2nd one thanks for the effort in drawing....
Thanks for all the standard 10 year series a level answers but anything for a simple guy like me? -
when u pull from side, the string will pull on the weight cuz the string cant extend. u calculate the force on the string by using trigonometryOriginally posted by banzie:Let say a weight is 1000kg Then it is hang by a string what is the force required to pull the weight from a pendulum
Basically means it is tied to a string how much force you need to pull it from the side. I know to pull it up is 1000kg by what about 90 degree to the side leh?
Issit 500kg? or what? -
Wat talking u???Do u mean the string is attached to the 1000kg mass??Originally posted by banzie:Let say a weight is 1000kg Then it is hang by a string what is the force required to pull the weight from a pendulum
Basically means it is tied to a string how much force you need to pull it from the side. I know to pull it up is 1000kg by what about 90 degree to the side leh?
Issit 500kg? or what?
Suppose all the angle is with respect to the vertical....for angle less than 5 degrees....use equations of simple harmonic oscillation(sho).....for large angles...shm do not work anymore....
And if the case is (mass)--------String--------(pivot)
{90 deg to vertical line in dig above}
the string provides NO FORCE to support the mass at 90 degrees......
Suppose for circular motion, as what tammy said...the angle cannot be 90 degrees too if the centripetal force is provided by the string...
In short,for any composite system, we can always decompose the total force into any 2 perpendicular directions because the effect of net force is work done and work done=(vector force)dot product(displacement)....Hence 90 degrees displacement from a certain force means subsequent motion along that 90 degrees path has NOTHING to do with that force.,,
In a sense for any 2 dimensional mechanics, the any 2 perpendicular force can act as a basis( linear algebra) to span the entire possible set of motions in vectorial sense.
Sorry for late reply cos I am too troubled over what is happening in AA
And pls provide a diagram so that other forumers can help u out more easily....
Correction to diagram cos it comes out quite differently in actual post
-
Correct( if u refer Fa as horizontal component of string).....notice as @=90 degrees.....Fa(which is =Fbsin@) tends to infinity and Fbcos@=0Originally posted by le cruz:If
Fa = force exerted from side of pendulum
Fb = tension in string
G = gravitational force
@ = angle between vertical datum and string
Fb cos @ = G
Fb sin @ = Fa
Fa = G sin @ / cos @ = G tan @
Plot Fa = G tan @ for @ = 0° to 90°
This implies it is not physically possible to have the string alone to provide force for the mass to be 90 degrees to the vertical......Unless the string can provide infinity amount of force -
depends on how you do it lor. technically if you keep applying liek 1 nN force at the right time, you can get the pendulum up to 90 degrees
-
??? From other sources of force possible....Originally posted by hisoka:depends on how you do it lor. technically if you keep applying liek 1 nN force at the right time, you can get the pendulum up to 90 degrees
From the string is not possible unless U have magic power... -
TS, ur qn like not full leh.
-
x2Originally posted by jay_rocks:TS, ur qn like not full leh. -
Cruz got the right idea, you must seperate the vectors of forces present in experiment.Originally posted by le cruz:If
Fa = force exerted from side of pendulum
Fb = tension in string
G = gravitational force
@ = angle between vertical datum and string
Fb cos @ = G
Fb sin @ = Fa
Fa = G sin @ / cos @ = G tan @
Plot Fa = G tan @ for @ = 0° to 90° -
Yes i remember this question in my A level exam. Year 2001?Originally posted by eagle:Excellent answer. This is the correct answer.
This question is a standard and simple question from A levels, making use of the knowledge of trigo and resolution of horizontal and vertical forces.
The way TS asked the question is really silly. He should just copied and pasted the whole question instead of making us guess. Dividing mg into horizontal and vertical component. Yawnz. That's how easy A level physics is. -
pendulum. the idea is to get the weight to the 90 degrees lvl but no requirement to keep it there.Originally posted by Hamiltonian1125:??? From other sources of force possible....
From the string is not possible unless U have magic power...
so you could jsut apply a huge force and get it up to that level or you could push abit and push abit more every time the pendulum comes to rest in the right direction -
Physics arh? Go ask the resident SgF Physics consultants in Papercut & Fudgester lor...... Theu super steady wan ok?
-
I get u...u mean to get it just to 90 deg motion by external force...i.e to flip the pendulum with correct force so that it momentarily reached 90 deg?? Yesh that is possible.....Originally posted by hisoka:pendulum. the idea is to get the weight to the 90 degrees lvl but no requirement to keep it there.
so you could jsut apply a huge force and get it up to that level or you could push abit and push abit more every time the pendulum comes to rest in the right direction
But I was talking abt other cases where forces is only due to the string....
Yup u are right! -
Originally posted by :Physics arh? Go ask the resident SgF Physics consultants in Papercut & Fudgester lor...... Theu super steady wan ok?
sees arrow flying at the engine duo
-
Thanks for so much arguement and etc etc...
I still don't get it.....
I just want to know how much force need to pull the person to the side of the swing only!?... also so hard...
-
wat tokin u?
-
If u mean the horizontal force to pull the person and stay in eqm ,then the ans is F=-Tsin@, where F is the ext force acting opposite to that of tension(T) horizontal component and @ is the angle made to the vertical.Originally posted by banzie:Thanks for so much arguement and etc etc...
I still don't get it.....
I just want to know how much force need to pull the person to the side of the swing only!?... also so hard...
Typo... -
i see most people here dunno the solution in the first place and then when someone post the correct answer, many then come in and give comments and add on this add on that, question not clear, giving vague answers but not working the answer out, etc etc etc, saying this so easy blab blab blab....
If the question is not clear then how in the first place the correct answer was posted?
Let's see how many will flame me. whahahaha