Question

Please help with this question ..

Answer 1

http://screencast.com/t/Ts85aEgJgALn

Answer 2

@UnkleRhaukus @ParthKohli

Answer 3

I don't know Physics. UnkleRhaukus will definitely be able to help ya in any case.

Answer 4

okay thanks

Answer 5

i think you need to convert those diameters to radii first

Answer 6

okay and then

Answer 7

then draw the forces onto the diagram

Answer 8

then i think you have to equate the tension due to Q with a torque on P

Answer 9

Torque on P = Moment along P ?
3 = T * 50 * 10^-3 is it right

Answer 10

i dont think so

Answer 11

then?

Answer 12

i dont know

Answer 13

I think it is D.

Answer 14

First of all to calculate the tension :

\(\tau = T \times r_1\)
We have \(\tau\) = 3 N m
and \(r_1 = 5 \times 10^{-2} m\)

Put these values and calculate the tension.

Answer 15

Can you tell me what you get?

Answer 16

@zaphod . You have to just plug-in the values :
\(3 Nm = T \times 5 \times 10^{-2} \)
\(T = \cfrac{3}{5 \times 10^{-2}} \)

Can you tell me what is T now?

Answer 17

60N

Answer 18

Great work! So I have one part as 60 N... That is sure that it will be D option

But though let us calculate the second part...

\(\tau = T \times r_2 \)

We have T = \(60 N\) and \(r_2 = 75 \times 10^{-3}\)

Calculate \(\tau\) now.

Answer 19

i can do it.. Torque = one of the forces * perpendicular distance between the two forces right...then why do we take distance as r?

Answer 20

That is the same thing... the perpendicular distance between the two forces is radius.

Answer 21

See
\(\tau = F R \sin \theta \)
That \(R \sin \theta\) is the perpendicular to the two forces..

Answer 22

Is it clear to you now @zaphod ?

Answer 23

diameter is supposed to be the pependicular distance right

Answer 24

can u show it in a diagram please

Answer 25

See in the Q : the motor is connected to the center so we have the perpendicular distance as the radius...