Newtons Law of Universal Gravitation (1 Viewer)

[steve001]

Hey,

I just need help with questions 8 and 9 from Chapter 4 in the Jacranda textbook.
For people that dont have the textbook the questions are:

8.(a) Discuss the reasons why Newton's Law of Universal Gravitation is important to an understanding o the motions of satellites.
(b) Describe how the use of this law allows calculation of the motion of satellites.

9.(a) State the nature of the slingshot effect or planetary swing-by.
(b) This is also known as a 'gravity-assist manoeuvre'. Briefly describe the role of gravity in this manoeuvre.
(c) State the laws of physics underlying this effect.
(d) Identify the benefits achieved by this manoeuvre.

Thanks in advanced

 

[water89]

Hey Steve how you going.

WEll in answer to your NEwtons law question, the answer is via newtons law of gravitation we were able to mathematically model orbits. Although Kepler came before Newton his Law was simply literary based through Newtons law of gravitation we were able to mathematically derive keplers law of periods.

This leads on to your second question about Newtons law of gravitation, because we were able to derive Keplers law of orbit mathematically subsequently we were also able to find out information on orbits, orbital periods, et etc. (Im assuming you know keplers law of periods)


your 2nd question

a) The slingshot effect allows space probes to utilise a planets angular momentum to increase speed and change trajectory (AHAHA "swing-by" jeez ive never heard of it be termed like that before)

b) OK heres essentially what happens. A space probe approaches the planet in the same direction as its orbital path (usually from the back) now DUE TO THE PLAENTS GRAVITY it is pulled in and accelerated, it then undergoes an elastic collision with the planet (one where no kinetic energy is lost) by doing this it gains angular momentum. USing the formula, momentum = MV you can see that a small change in the planets large velocity will give rise to a massive change in the probes velocity (as via the law of conservation of momentum in a closed system momentum must stay the same). So the velocity of the probe realtive to the plaent remains the same but the velocity of the probe relative to the sun changes (and thats what we want).

c) Law of conservation of momentum, law of conservation of energy

d) We are able to use the orbital path of a planet to change a space probes trajectory and speed it up.

Hope this helped! Have funn!