9http://www.feynmanlectures.info/
the great Richard feynmans buk itself has so many errors
HC Verma may also make mistakes in the same sense
LET THE MASS OF EACH KID BE 15 KG,DISTANCE BETWEEN THE POINTS OF ROD WHERE THE TWO KIDS HOLD IT BE 3.0 m AND
THE ROD ROTATES AT THE RATE OF 20 REVOLUTIONS PER MINUTE.FIND THE FORCE OF FRICTION EXERTED ON THE ROD BY ONE OF KIDS.
-DIAGRAM FOLLOWS NEXT
-
UP 0 DOWN 0 0 32
32 Answers
62the effective radius will be r+L/2 cos θ
also the force inwards will be F
so F=mv2/(r+L/2 cos θ)
also, mg=N
and F=μmg
now i think we can find theta in terms of all the other variables :)
99i ve caught byah 10 times making mistakes and he has caught be 100 times !!!
he makes silly mistakes (multitasker) and i too (hurry burry)
ur#23 was rude to me and stop anymore discussions on that
1#24(don edit it now...........ok)
there u said:
byah will realise his silly mistake
wat's it rude or sumthing else??????[16][16]
1if u had understood physics properly u wudnt shout like this ..............wat is this(rude or sumthing else??????)
1so HCV din give L(so u r intelligent and HCV stupid)..........u r wrong
wat's rude here u only told
ur words are so stupid
if u had understood physics properly u wudnt shout like this
in ur original Q(#1) itself im saying that ans in #4 is wrong( byah will realise his silly mistake ) . acc to #1 the boy MUST tilt to balance torque
n i replied........
so HCV din give L(so u r intelligent and HCV stupid)..........u r wrong
wat's rude[16][16]
1see in #21 -----general discussion
#23------mild
#25------coz of this line u posted in #24 ur words are so stupid
1ur words are so stupid
so HCV din give L(so u r intelligent and HCV stupid)..........u r wrong
9ur words are so stupid
if u had understood physics properly u wudnt shout like this
in ur original Q(#1) itself im saying that ans in #4 is wrong( byah will realise his silly mistake ) . acc to #1 the boy MUST tilt to balance torque
1I DON KNOW WAT THE HELL U R TALKIN..........READ THE THREAD CAREFULLY..........DUDE...........WE R NOW TALKLING BOUT THE SECOND CASE WHICH IS CLEARLY MENTIONED IN #12 BY ME.AND NISHANT SIR HAS GIVEN LENGTH OF BOY ALSO...............GOT IT????????
U R POSTING UNNECCESARY THINGS INSTEAD IF U HAD READ THE THREAD PROPERLY I WUD NOT HAVE NEEDED TO TELL U THIS.
9know u dint make a new Q
the boy must tilt at an angle to balance torque
so ans in#4 is wrong
jus substitute values in #20 ull get ans
FBD is easy to visualise
1celestine read #13 :-)(length is given)
this is a new ques. of old one made by NISHANT SIR...................
post ur complete solution along with FBD
9JC post source of Q
Q is incomplete without lenght of man
f isnt mw2r its mw2(r +Lcos@/2)
also tan@ =mg/f (resolution of vectors)
so u can find f only wen L is gvn
1sir what is theta and the direction of various forces(plz post the FBD too)
62sorry john for the late reply
can you show me a couple of steps?
1i m getting inclination with vertical as tan-1[(2pi2/3g)-friction coeficient]
i need value of friction coefficient.y was height given by u?i din use it newhere
i know it is wrong.plz tell me corret method.
62John.. try that case yourself
Given that the height of the boy is 2 m
find the inclination of the boy and the new FBD etc! ;)
1@nishant sir
but if the boy was to slant due to rotation by an angle then the answer would have changed!
plz provide the ans. if the boy was to slant due to rotation by an angle
1itz
mw^2r ..........
m u noe
r u noe
w =20 *2pi /60
T ....... is d tension ie d force due to one kid.......
n nt two....... dohno ke wajah se woh nullify hoga
62dude.. there is no tension on the boy due to rod
tension is the property of the rod.. it is internal to the rod
same with hand...
there is only frictin
1i dont get the clear picture of the swing !
yeh bacche kya us rod par latke hain?
62which tension!!
Draw the FBD
the boy is catching the thing with his hand..
so the force on the merry go round will only be friction
tension will be in the hand of the boy
here is the question says that the boy is vertical then tehre is no probelm
but if the boy was to slant due to rotation by an angle then the answer would have changed!
1yup!but my query is that in this ques. y we don take tension into account
can u give some authentic explanation for not taking tenison into picture
62The friction acts inwards on the child
and r=3/2
while ω is given by 20x2π/60
M=15