[填空题]
1.A space probe lands on t2cxi63x v ysh-q ida )a-y 2j2s1pr4kl7d bfh4ie;;kg-gukx :jn k2)mhe surface of a planet which has the same radius as th:kum-7;nj bfkd;)4xge2gk i he Earth, and a gravitational field strength of $6.7\, N\,kg^{−1}$ at its surface.
(1)The mass of Earth is given as $5.98\times10^{24}\,kg$. Show that the planet’s mass is approximately $4\times10^{24}\,kg$. $m_{planet}$ = $\times10^{24}kg$
(2)The average radius of the planet is $6.37\times10^3$ km. Calculate the planet's average density in SI base units.
(3)The planet is at a distance of $1.43\times10^{11}\,m$ from the Earth. Calculate the gravitational force between the Earth and the planet.
3.(1)Calculate the magnitude of the resultant gravitational field strength between the planet and the Earth at point $X$, which is located $\frac{1}{3}$ of the total distance between the planets when measured from the Earth. $g_{planet}$ = $\times 10^{-9}N\,Kg{-1}$
(2)Suggest a reason why your answer above is only an estimate.
3.(1)The planet has a moon with an orbital radius of $1.20\times10^7\,m$. Show that the acceleration of this moon is approximately $1.9\,ms^{−2}$.
(2)Calculate the angular speed of this moon.
(3)Determine the orbital period of this moon, in hours. h = $h$
