Question

a satellite s is moving in an elliptical orbit around the earth . the mass of satellite is very small compared to mass of earth.
a) accelaration of S is always directed towards the centre
b)angular momentum of S about centre of earth changes direction, but not magnitude
c)total mechanical energy changes
d)linear momentum of S remains constant in magnitude

Answer 1

angular acc is always toward centre but tangential acc is always perpendicular. so (A) is False. Center is a special point where direction and magnitude both are constant. Direction is always parallel to the axis. so (B) IS FALSE. since no net external force is acting energy is conserved. so (C) is false. Linear angular momentum depends on direction and magnitude of velocity and direction of velocity in a circular orbit is continuously changing, so linear momentum changes. (D) IS CORRECT

Answer 2

*linear momentum changes but remains constant in magnitude so (D) is correct.

Answer 3

@goutham1995
The above explanations are not correct.

According to N's 2nd law, acceleration is proportional to force, hence acceleration of S is always pointing at the centre of the Earth.

D is not correct: linear momentum changes direction AND magnitude.

Answer 4

IN UNIFORM CIRCULAR MOTION, LINEAR MOMENTUM CHANGES BUT KINETIC ENERGY DOES NOT CHANGE.
IN UNIFORM CIRCULAR MOTION, DIRECTION ALWAYS CHANGES.THEREFORE LINEAR MOMENTUM WHICH IS A VECTOR QUANTITY ALSO CHANGES. BUT AS THE (MAGNITUDE) VELOCITY AND MASS REMAINS CONSTANT , K.E. WHICH IS A SCALAR QUANTITY ALSO REMAINS CONSTANT.

Answer 5

so if linear momentum changes in both direction and magnitude this means that magnitude of velocity is also changing so the K.E ENERGY WILL ALSO CHANGE BUT IT IS NOT POSSIBLE. (pls correct me if i m wrong sir)

Answer 6

@Rdx:
What you are saying is true for CIRCULAR motion of the satellite, but Goutham's question is more general as it is specifically said that the orbit is ELLIPTICAL.

In this kind of motion, KE, gravitational PE, speed, magnitude of linear momentum, altitude, magnitude of acceleration, are not constant.

Answer 7

ohh poop sorry generally i totally considered it irrelevant to see that satellite is mentioned. YES SIR U ARE COMPLETELY RIGHT AND THANK YOU FOR CORRECTING ME. I REVISE MY KEPLER'S LAW. XD