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[Thirdfront]

no dear, that tension is not the centrifugal force but in fact that tension is generated (due to the weight of a body) as a reactionary force to/against the applied force on the body which is rotating it in a circle ...

you should not mix tension & so-called centrifugal force with each other as the former is a pure force whereas the later one is just an effect felt only in presence of a centripetal force ...

if this reason alone doesn't satisfy you so just try to check whether the centrifugal force conform to newton's 3rd law of motion ...

In the case of string and mass (sling shot like scenario), centrifugal force is very much real and obey newton's 3rd law (reaction to centripetal) but exerted on the string by the mass (string pulls the mass, mass pulls the string)

 

[faisal6309]

 

[kbd-raaf]

im not sure but just my logical guess is the object would just simply goes on to drop down to the bottom of the earth ...


There is no such force as Centrifugal force , it just simply do not exist because it does not comply to the newton's 3rd law of motion which states that : "action and reaction forces act in pair but they never act on the same body".

centrifugal force - Physics Forums Library

Centrifugal force is a fictitious force. I.e you need to be in an inertial coordinate frame to witness it. There are no inertial coordinate frames in the known universe. The planet is generally considered to be an inertial CF but in truth it is moving relative to the sun which is moving relative to the galaxy etc.

Centrifugal force DOES exist. We just can't measure it or observe it yet.

 

[t_for_talli]

1.consider a simple pendulum with a bob of mass m ,and string of length l.it is executing an shm.at it's extreme the height of bob from its mean position is y c.m.and at the mean position it has a velocity of v cm/s.what is the net force on the bob at the mean position?

2.if the bob is filled with water and it has a hole at its bottom will there be any change in its time period if so how??

1. Tension = mv^2/L + mg or 2mgy/l +mg (net force will be zero)
2. No as T=2pie(l/g)^.5 so time period doesn't depends on mass

 

[t_for_talli]

heres mine..consider earth..in which a hole is dug along its diameter through out. now..if u drop an object in the hole..what might happen!!!

Object will experience to and fro motion between ends of hole

.5*m*Vcenter^2= Integration(x=R to 0) of {(G*M*m/x^2)*((R-x)/x)^3)dx}

# assuming mass of earth is evenly distributed over the volume

now after passing center of earth same force will act opposite to the motion resulting in zero velocity of the object at the other end of the hole leaving it with a gravitational pull towards the center and this process will repeat infinitely.

But the motion will not be SHM as f(at any point x units from center)= (G*M*m/x^2)*((R-x)/x)^3) is not directly proportional to x.

 

[neehar]

2. No as T=2pie(l/g)^.5 so time period doesn't depends on mass

but it depends on centre of mass!! as the water level decreases the centre of mass moves down and so the length of the pendulum increases so the time period increases but when the bob is emptied completely the centre of mass returns back to the centre and so time period decreases and comes back to the original position

 

[MuZammiL Dr. s[1]n]

In the case of string and mass (sling shot like scenario), centrifugal force is very much real and obey newton's 3rd law (reaction to centripetal) but exerted on the string by the mass (string pulls the mass, mass pulls the string)

heard ur p.o.v. ; then tell me : q.-1 whether the centrifugal force acts on the ball or not ?
q.-2 does the centripetal force act on the same ball or not ?

 

[MuZammiL Dr. s[1]n]

my next analytical question is :-
q.-2 : an intake valve opens when the crank. is 13 degrees before t.d.c. & closes at 48 degrees after b.d.c. . How many degrees did the crank. move on the intake stroke ?

 

[NP-complete]

Surprised by the confusion on centrifugal force here. Its a pseudoforce, also called fictitious force as mentioned in a post above. These forces are observed in a non-inertial reference frame.
( inertial frame of reference : one in which law of inertia holds. newtons laws of motion are for this reference frame.
non-inertial frame of reference : one in which law of inertia does not hold.)
pseudoforces dont exist for an observer in an inertial reference frame.

 

[t_for_talli]

but it depends on centre of mass!! as the water level decreases the centre of mass moves down and so the length of the pendulum increases so the time period increases but when the bob is emptied completely the centre of mass returns back to the centre and so time period decreases and comes back to the original position

Agreed, I was talking about steady state scenario

 

[Thirdfront]

heard ur p.o.v. ; then tell me : q.-1 whether the centrifugal force acts on the ball or not ?
q.-2 does the centripetal force act on the same ball or not ?

1. no (I am not referring to apparant force here)
2. yes

Surprised by the confusion on centrifugal force here. Its a pseudoforce, also called fictitious force as mentioned in a post above. These forces are observed in a non-inertial reference frame.
( inertial frame of reference : one in which law of inertia holds. newtons laws of motion are for this reference frame.
non-inertial frame of reference : one in which law of inertia does not hold.)
pseudoforces dont exist for an observer in an inertial reference frame.

There are 2 centrifugal forces. 1 that you have describe, 2 as a reactive to centripetal force. While the first one is fictitious/apparent force, second one is pretty much real.....

my next analytical question is :-
q.-2 : an intake valve opens when the crank. is 13 degrees before t.d.c. & closes at 48 degrees after b.d.c. . How many degrees did the crank. move on the intake stroke ?

231 degrees....

 

[MuZammiL Dr. s[1]n]

1. no (I am not referring to apparant force here)
2. yes


There are 2 centrifugal forces. 1 that you have describe, 2 as a reactive to centripetal force. While the first one is fictitious/apparent force, second one is pretty much real.....


231 degrees....

way wrong answer ; right one is : = 241 degrees. of Crank. rotation ...

 

[Dash]

Here is mine..

What would have been our numerical system?, if human being had 11 fingers.

 

[Thirdfront]

way wrong answer ; right one is : = 241 degrees. of Crank. rotation ...

Oooops.... mistake in addition... 13+180+48 = 241 and not 231.....

 

[MuZammiL Dr. s[1]n]

Oooops.... mistake in addition... 13+180+48 = 241 and not 231.....

what's ur edu. background ?
i'm a qualified professional TexTiLe (-ngr. and currently studying automotive engg. ...