A2 Physics Doubts- URGENT!

[ShootingStar]

Please help me out with the following questions:

1) Two satellites orbit a planet of mass 'M' with Time periods of 3 days and 4.5 days, respectively. If the orbital radius of the first satellite is 2x10^6 m, determine the radius of orbit of the other. (Answer is 2.62x10^6)

2) A mass 'm' is moved from the North pole towards the equator. If the Earth is assumed to be a perfect sphere of radius 'R' , and if the mass moved is exactly 60kg, determine the difference in weight when measured at the North pole and at the equator.
R = 6.4x10^6 m
M of Earth = 6.0x10^24 kg
G = 6.67x10-11
m = 60 kg
( Answer is 2.0 N )

3) An astronaut travels from the Earth towards the moon where he experiences no net force. Determine the distance from the surface of the moon where this phenomenon occurs. Given that,

- the radius of the moon is 1.74x10^6 m
- mass of the moon is 0.0735x10^24 kg

(Answer is 3.71x10^7 m )

Please help me out.. i desperately need the explanation for these quesitons...

 

[ShootingStar]

anyone?

 

[yaogeorge]

1. since they orbiting around the same planet. centripedal force=gravitational force

using mrw^2=GMm/r^2
r^3w^2=GM
plug in this formula for both satellite. then solve simultaneously. u will get the answer.(kepler's 3rd law)

 

[ShootingStar]

please help me with the last two questions aswell...

 

[ShootingStar]

Need help with the following questions from the topic Oscillations...

1) The frequency of and oscillation is 795.775 m Hz. The amplitude of oscillation is 2 m.
Find the instantaneous acceleration of a pendulum and its angular displacement after exactly 0.675 s.

2) The maximum amplitude of a body in simple harmonic motion is 0.7854 m, where the time period is 4 s. Sketch with complete labelling the graphs of

- x vs t
- v vs t
- a vs t