MORE Physics Help: Space Topic (2 Viewers)

clissold · Jan 19, 2011

Hey..

It would be greatly appreciated if anyone could give me any assistance whatsoever on the following questions. Worked solutions to the questions would be ideal please.

2.3.2 A projectile has a time of flight of 7.5s and a range of 1200m. Calculate:

a) its horizontal velocity
b) its maximum height
c) the velocity with which it is projected

2.6.2 A rocket is accelerating from a launch pad at 26.95m/s/s.

a) calculate the g force on a 60kg astronaut
b) calculate the g force on a 80kg astronaut

2.6.3 A rocket is accelerating from between Mars and Jupiter at 26.95m/s/s. Calculate the g force on a 60kg astonaut.

2.11.2 A 150kg satellite is orbiting Earth at an altitude of 272km. Its orbital period is 90 minutes. Given that the diameter of Earth is 12 576km, and its mass is 5.974*10^24kg, calculate the centripetal force on the satellite.

2.14.5 Calculate the orbital speed of the Earth around the Sun given the mass of the Sun is 1.99*10^30kg, and its diameter is 1 392 530km. The mas of the Earth is 5.974*10^24kg, its diameter is 12 756km, and the distance between the Sun and Earth is 150 000 000km.

Thankyou

ohexploitable · Jan 19, 2011

ohexploitable · Jan 19, 2011

ohexploitable · Jan 19, 2011

ohexploitable · Jan 19, 2011

ohexploitable · Jan 19, 2011

FCB · Jan 19, 2011

ohexploitable said:
$\\2.11.2\\r=(6378+272)\times10^3=6.65\times10^6\text{ m}\\C=2\pi r=2\times\pi\times6.65\times10^6=4.18\times 10^7\text{ m}\\v=\frac{d}{t}=\frac{4.18\times 10^7}{90\times60}=7740.74\text{ ms}^{-1}\\\\F=\frac{mv^2}{r}=\frac{150\times7740.74^2}{6.65\times10^6}=1350\text{ N, directed towards the centre of the Earth.}$

I dont know how to use latex...

But it would be far simpler to just simply use the formula
F=Gmm/r^2

Sub in the numbers and you cant really go wrong. But i am sure that people appriciate your help alot.

clissold · Jan 20, 2011

Thankyou so much "ohexploitable"

Your worked answer were of great help to me..

However I do have a few questions for you..

In question 2.6.3, why does g equal 0..? It turns out to be the correct answer although I thought there would be some value for g.

In question 2.11.2, I do not completely understand this working because I havnt been taught this way..?

In question 2.14.5, your answer does not match the answer in the back of my book..?

ohexploitable · Jan 20, 2011

clissold said:
In question 2.6.3, why does g equal 0..? It turns out to be the correct answer although I thought there would be some value for g.

Because there is no gravity in space.

In question 2.11.2, I do not completely understand this working because I havnt been taught this way..?

Look at FCB's post, my way was retarded, the question said centripetal force so I kept on thinking of the centripetal force formula.

In question 2.14.5, your answer does not match the answer in the back of my book..?

Wikipedia says the average orbital speed of Earth is 29.78 km/s.

http://en.wikipedia.org/wiki/Earth

Dot Point Physics answers has lots of mistakes.

clissold · Jan 20, 2011

ohexploitable said:
Because there is no gravity in space.

Hahaha, good point.. I was just confused because I though there would have been some gravitational force exerted by either of the planets but I see where your coming from.

Look at FCB's post, my way was retarded, the question said centripetal force so I kept on thinking of the centripetal force formula..

Yeahh I did have a look at the post by "FCB" but I didnt think that made sense either..? If "FCB" could explain that to me with a worked solution that would be much appreciated.

Wikipedia says the average orbital speed of Earth is 29.78 km/s.

http://en.wikipedia.org/wiki/Earth

Dot Point Physics answers has lots of mistakes.

+1 .. no wonder I get confused

ohexploitable · Jan 20, 2011

clissold said:
your

grr...

Yeahh I did have a look at the post by "FCB" but I didnt think that made sense either..? If "FCB" could explain that to me with a worked solution that would be much appreciated.

$\\F=G\frac{m_1m_2}{r^2}\\F=6.67\times10^{-11}\times\frac{150\times5.974\times10^{24}}{[(6378+272)\times10^3]^2}\\F=1351.57\text{ N, directed towards the centre of the Earth.}$

clissold · Jan 20, 2011

ohexploitable said:
$\\F=G\frac{m_1m_2}{r^2}\\F=6.67\times10^{-11}\times\frac{150\times5.974\times10^{24}}{[(6378+272)\times10^3]^2}\\F=1351.57\text{ N, directed towards the centre of the Earth.}$

Thankyou heaps..

Lastly, I believe that you are doing your HSC this year and the subjects that you actually do are different to those in your sig. You come across as one of those people who are gonna get like 99.95 ATAR easy (well to me anyway) so I was just wondering if you had any tips on how to study effectively or even how you manage to remember all of this stuff for physics..?

ohexploitable · Jan 20, 2011

clissold said:
You come across as one of those people who are gonna get like 99.95 ATAR easy (well to me anyway)

lol, not with my English marks.

so I was just wondering if you had any tips on how to study effectively or even how you manage to remember all of this stuff for physics..?

I'm just gonna repeat what everyone will say - do lots of past papers.

clissold · Jan 20, 2011

ohexploitable said:
lol, not with my English marks.

I'm just gonna repeat what everyone will say - do lots of past papers.

Ohhh sorry, only 99.50..

and yeahh thanks, Ill try to do as many past HSC papers as possible.

jyu · Jan 24, 2011

What is meant by g force? Does it stand for force of gravity?

ohexploitable · Jan 24, 2011

jyu said:
What is meant by g force? Does it stand for force of gravity?

G-force is a measure of acceleration.

jyu · Jan 28, 2011

G-force is a measure of acceleration not counting the force due to gravity. Is there a g-string in the string theory?

MORE Physics Help: Space Topic (2 Viewers)

clissold

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ohexploitable

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FCB

Emma Watson <3

clissold

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clissold

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clissold

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clissold

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jyu

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