Mechanics (1 Viewer)

[Fade1233]

Wondering as to conical pendulum, when are the tensions same and when are they not. for eg. if it is from a pulley then are they same or are they same when the similar strings connected to each other (inc. length) or when similar strings are connected to the mass or only when they tell u?
max reps for useful help.
Thanks

 

[gahyunkk]

I was wondering about this as well

 

[Carrotsticks]

General rule of thumb, one string = one tension. Two string = two tensions etc.

 

[Fade1233]

General rule of thumb, one string = one tension. Two string = two tensions etc.

Does it matter- the ratio of length from the adjoinment place? Like if 20 and the other one is 30 cos my teacher said they should be equal length?

 

[braintic]

If there is mass or resistance anywhere along the length of the string, then the tension will not be constant.

ALL HSC questions assume massless strings, because any distribution of mass along the string will affect the tension.

But a type of question that is allowed is two (massless) strings tied to the same mass. In that case (in general) the tension in each string is different.

With regard to pulleys, all HSC questions assume massless and frictionless pulleys. So they are not real pulleys - the string does not roll with the pulley because that would require the concept of angular momentum. Instead it is free to slip over the pulley without friction. In this case, as the pulley does not offer any resistance to the motion, the tension will be the same on either side. If anything impedes that motion, then the tensions will not be the same on either side.

So the key is to look at the tension in each length of string between obstructions of mass and/or friction.

 

[emilios]

So in basic terms, when CAN you assume tensions to be equal? Only when a pulley is involved?

The lack of clarity on this issue is really annoying. My trials tomorrow :/