23yes varun seems correct ,
if dv/dt ≠0 , such that magnitude wise also dv/dt≠0, then that means there is an accn parallel to v, hence C is correct and not A ....
A satellite S is moving in an elliptical orbit around the earth...the mass of satellite is very small compared to mass of earth....Which of the following is correct??
A. The acc of S is always directed towards the centre of the earth
B. Angular momentum of S about the centre of the earth changes in direction bt magnitude remains the same
C. Total mechanical energy of S remains constant
D. Linear momentum is constant in magnitude
It is a single correct option type question...acc to me the answer is C....bt in the buk its given to be A
plz explain!!!
this question is question number 43 in 2010 TMH...page number 9.7
-
UP 0 DOWN 0 0 27
27 Answers
1better than that .....ω doesnt change its dxn.. [ L=Iω ]
231since it is an eliptical orbit then obviously it has perigree n apogee so vel n speed changes so thefore it has tnagential acc
c is the rite answer
1yar..nw i may sound stupid to everyone....but plz don think m fooling around here
but....isn't the acceleration having two parts...one centripetal...and the other tangential...and only the centripetal is directed towards the center...
@buddyboy...i would have answered c
1@jsg...its k yaar...chalta hai..
@aveek n qwerty...yeah me too think its A n C...bt qwerty has specified the problem
if u ppl dint know the answer...n had to mark only 1 answer...wat will be ur best answer??
1ok guys here it goes......the direction of the cross-vector product vxr is always out of the plane of paper........so the direction won't change.
so B won't be the answer .
1A is right.
The acceleration is centripetal....so you've got A right.
23if torque is zero , ang momentum cant change aveek ,
u say v is changing , and wat about r ??
1oops!...i'm really sorry ..buddyboy , please forgive me..i didnt actually mean it.sometimes it just happens to me [ thank you Nishant bhaiya for making me realise my mista ke ! ]...anyways i hope that u understood explanations given by me and others..all the best [ and once again sorry ! ]
1B nahi hoga yaar
direction of angular momentum nahi change hoga
1buddyboy......don't be disheartened dude.....
anyways jsgenius is 100% correct in his explanation.
energy is -GMm/2a (a = semi-major axis) which is constant.
similarly..as
F = GMm/r2 passes thru S ... net torque about S is 0....so conserve angular momentum.
and A is as i had explained..... :-)
1@jsg...i get it...
bt in that case option B for this question isnt correct!!!
the reason for C not being correct is that KE n PE keep varying...bt according to me...though PE n KE keep varying...bt total mech energy is the same ryt??....so C shud be correct!!!
wat will u mark if u dint know the answer n had to mark just 1 answer??
@nishant bhaiya
many thanx 4 da support...it does hurt...bt in a way he is correct...i hav been lazy all my 11th std...bt now m actually working quite hard!!!
so in a way...i m new to studying!!!..
62dear jsgenius..
I am sorry if i sound harsh.. but please avoid to use phrases that makes someone feel let down... "please go and study theory"
I am sure you will not like someone else say this to you...
you should appreciate that the person who you are replying to may be very new to studying... may have just started preparing and you would not want to deter him from studying by making him feel bad...
1arrey,please go and study theory...here net TORQUE = 0...so angular momentum is conserved !
1hows angular momentum same in magnitude wen velocity keeps changing w.r.t. radius of the orbit??
1ok..i think ans is : A,B,C
A: reason given by Aveek
B:reason..given in theory...[i hope u know it ]
C:True as external force and non-conservative internal forces are absent [ME=constant]
D:WRONG..velocity changes but mass remains constant..so P changes
1A is correct...no doubt abt that...bt i still doubt the reason that energy is dissipated into space!!!
in that case satellite will slow down...lose velocity...hav a free fall under influence of gravity!!!