can somone help with q9 ?
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aqa physics multiple choice question q9 watch
- Thread Starter
- 31-05-2016 14:55
- Official Rep
- 02-06-2016 16:10
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Just quoting in Puddles the Monkey so she can move the thread if needed
Spoiler:Show(Original post by Puddles the Monkey)
- 05-06-2016 23:10
The volume of the spherical planet is 4/3 * pi * r^3 where r = R in this case. Therefore the volume is 4/3 * pi * R^3. Since the planet has a uniform density of P, and mass = density * volume, the mass of the planet is 4/3 * pi * R^3 * P. The distance between the centre of masses of the satellite and the planet is 2R because the radius of the planet is R and the satellite is R metres above the planet. Using the 'force between two masses' formula where m1 = 4/3 * pi * R^3 * P, m2 = m and r = 2R, you get (G * 4/3*pi*R*p * m) / (2R)^2. Cancel all that down and you get G*pi*R*p*m / 3. This is answer ALast edited by A_A123; 05-06-2016 at 23:12.
- 09-06-2016 23:02
You had to cross it out