torque and force (1 Viewer)

[mr EaZy]

if the coils of a motor is in a horizontal plane, the force is max, but at the same time, is torque max as well?

thnx in advance

 

[helper]

Force is constant.

Torque is max horizontal and zero right angles.

 

[JayWalker]

Force is constant.

Torque is max horizontal and zero right angles.

Hmm, Well, No your wrong.. Consider Vector triangles, the force is less when its nearing an upright position, not to mention if the non-use of curved pole pieces is not taken into consideration....

And Torque relied on Area so your right about the second part, but thats not what he asked..

t = nBIlCos0
F = BIlSin0
Therefore they rotate... Hence, when F is max, t is min.. Visa Verce. BYE!@

 

[helper]

Wrong Jaywalker
Remember what theta is in the first equation

In F=BILsintheta.
Theta is the angle the wire makes with the magnetic field. It remains perpendicular in a motor.

 

[JayWalker]

Wrong Jaywalker
Remember what theta is in the first equation

In F=BILsintheta.
Theta is the angle the wire makes with the magnetic field. It remains perpendicular in a motor.

Can i ask you a quesiton?
Do you read the posts before you post..

Your stupidity is showing..
First of all, 0 => THETA, for my prev example..

F = BIlsin0

t = nBIAcos0

Therefore as 0 changes, they both reverse.. fucking idiot.. get a CLUE!! HONEST TO GOD, dont post your stupidity here...

And I also said this.. "not to mention if the non-use of curved pole pieces ...." So its not always perpendicular because he did not SPECIFY if they were curved..

For GODS SAKE!! GET AN IDEA PLEASEE>> YOUR KILLING ME!

 

[helper]

Jaywalker

Look at your notes and you will find theta in the two equations are different.

F=BILsin0
0=angle with magnetic field. The two sides of the coil are always perpindicular to the coil, so F remains constant.

---> |
---> | is still perpindicular to the field
---> |

T=nBIAcos0
0 is the angle of the coil with the plane. It changes from 0 to 90, causing a change in the torque as the perpindicular distance the force is from the centre of rotation.

Check before you go off.

 

[gordo]

f=ma
f=ma
f=ma

 

[helper]

Net Force = ma
The net force changes but to look at that then we need to look at more than F=BIlsinO

Magnetic Force on each section is constant

Top View
B
-->
--> [] Horizontal two sides are perpindicular, So F=BIl o=90
-->

End on

-->
--> __ End of coil parallel to field so O=0, So T=nBIA. There would be a force on each side, one up and one down
-->

Rotated

Top View
B
-->
--> | Horizontal two sides are perpindicular, So F=BIl o=90
-->

End on

-->
--> | End of coil parallel to field so O=90, So T=nBIAcos90=o. There would be a force on each side still, one up and one down but no torque as the two forces are both acting through the centre of rotation. Hence net turning force is zero

 

[ashtor]

so does force change or not? coz i didnt understand one thing Jay and helper sed in their arguement...i got force is consntant in my notes coz the wire is always perpendicular to the field even when the coil rotates but torque changes coz Area does when it rotates

 

[helper]

What you said is correct ashtor, as the angles in the two equations mean something different

 

[mr EaZy]

hey helper, u doin the HSC this year?

i think, from ive heard in this thread is that force would be constant especially if the coil is in a radial field. is this right? i used to think that force changes because f=bilsin@. BIL is const and the @ =90 when the coil is in a vertical plane.

 

[mr EaZy]

hey ashtor, we did u get that from?

 

[superbird]

torque is constant in a radial field.

 

[Xayma]

In a non radial field.

The force always remains constant.

The torque changes as the perpendicular distance that causes the turning effect changes. Due to the principle of transmissibility of forces and as the force is always vertical it can be shown that the distance and hence the torque is maximum when the armature is horizontal.

Jaywalker the θ's refer to two different things, the forces θ is the angle between the coil and the magnetic field which is always 90° in the 3D plane present. It is more a consequence of poor choice of using θ for both.

 

[mr EaZy]

thnx for that: force is constant!!
i didnt know that but what is the significance of BIL SIN$

is that just for conductors in a field ? and not for motors correct?

 

[mr EaZy]

and jay walker, no offense but go easy on helper, he's just celebrated his 200th post. Thats 200 pieces of advice to us students

he should be awarded with a free BOS t-shirt!

 

[Xayma]

Conductor in a field. Such as one orientated / in a horizantal field.

In motors they will always be perpendicular as it is 3D. If you look straight down from above you would see that it is always 90° to the field lines.