Question

State that WORK is DONE or NOT.....

A Wind-Mill is lifting water from a well.

and also justify your answer..

Answer 1

am confusing.....plz help me

Answer 2

for windmill work is not done and for water work is done!

Answer 3

no @VV-EFF question is one!!

Answer 4

@sirm3d

Answer 5

work is done then! because windmill is applying force to pull up the water and the water itself displaces! now it depends on the angle between the force applied by the mill and the direction of water!

Answer 6

yaa.. i know but my teacher says the work done is zero..

Answer 7

she would be considering cosQ =0, then she's right

Answer 8

can you help me @ganeshie8 and @gerryliyana

Answer 9

what is this? i can't understand

Answer 10

workdone=FxDxcos(Q) where Q is the angle between the force F and displacement D.

Answer 11

the work done is zero., because windmills always return to the original point

Answer 12

how can we know that angle is of cosQ

Answer 13

yeah thats the point @gerryliyana ! he is considering water anf mill, both as a system!

Answer 14

and in case of water ! water is displaced by force!

Answer 15

work is done then! because windmill is applying force to pull up the water and the water itself displaces! now it depends on the angle between the force applied by the mill and the direction of water!
@gerryliyana in this case!!

Answer 16

nice @VV-EFF

Answer 17

so in that case...

Answer 18

nice What! @gerryliyana ! gve him the answer man! lol....

Answer 19

so finally whats the conclusion of this answer.

Answer 20

@Aperogalics have a look!!

Answer 21

the conclusion is that if u are considering the both as a system then the work is done ; iff Q is not equals to 1.5707. and if the system is only the mill then the work is said to be not done!!

Answer 22

but the answer is to be written is one

Answer 23

work is not done! then

Answer 24

in my solution book answer is work is done and the reason is that windmill pulls the water against the gravity...

Answer 25

@mayankdevnani there are two thing work done by the system and work done on the system here if the system is windmill then work done by the system is zero as there is no net dispacement while work done by the system is +ve as he make the water to be displaced........:)

Answer 26

obviously !!!!! @mayankdevnani if its against the gravity the according to the equation F=ma , water has mass and the acceleration is .9.8 mLsecsquare! then the force definitely exists ! and so the workdone!

Answer 27

so what's the answer??

Answer 28

now dude stop confusing your self! the answer is that the work is certainly done by the system!

Answer 29

m really confused @Aperogalics and @VV-EFF what is the concluded answer and answer should be one means both work done or not

Answer 30

so i am correct and my teacher is wrong!!!

Answer 31

yeah!

Answer 32

work is done by the system! its certain!

Answer 33

sure...are you sure about this!!

Answer 34

yeah!

Answer 35

let @Aperogalics be write and then think,. he has creative mind...let @Aperogalics be answer

Answer 36

@mayankdevnani @VV-EFF is very clever he is still saying work is done by the system if ur mam is talking about work done on the system then she is correct and if not then you are correct.........:)

Answer 37

no my mam says that the work be zero and i say that work is not zero @Aperogalics

Answer 38

lol.. what an answer @Aperogalics

Answer 39

@mayankdevnani yes ur mam says work is zero but is it by the system or on the system???????????
do you know about which she was talking about??????????????

Answer 40

no.. my friend george said that mam says the work done is zero

Answer 41

and also 1 thing

Answer 42

my senior friend also says that _____

"lifting water" is the work that is done. When anything is lifted - it is moved (displaced) upward against the force of gravity. The force that lifts the object (water) must be greater that that of gravity or the object won't displace upward. The Net force that acts upward to lift (object, water, etc) multiplied by the vertical lift height is defined to be the work done in this process.

Answer 43

secondly, there are not more than one work done... right..

Answer 44

lastly , what's the concluded answer suppose you are in examination hall and you have a pen and this question ...how would you solve it?
@Aperogalics and @VV-EFF

Answer 45

i would say that u plz read the conversation above! and conclude the answer urslf!

Answer 46

@mayankdevnani answer my question and you will get the answer by yourself:)

Answer 47

plz

Answer 48

a basic question in every book
suppose a man lifts a box to his head and walk 40kms .
IS THE WORK DONE BY THE PERSON?

Answer 49

no work done is zero

Answer 50

why????????

Answer 51

@mayankdevnani

Answer 52

because force acts in perpendicular direction\[90^{0}\] and displacement is at right angle

Answer 53

right @Aperogalics

Answer 54

is the work is done against gravity?????