Comparative and experimental investigations are two of three scientific investigations, the other is descriptive investigations.
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Explanation:
The planet Mars has two moons. Phobos and Delmos (i) phobos has period `7` hours, `39` minutes and an orbital radius of `9.4 xx 10^(3) km`. Calculate the mass of Mars. (ii) Assume that Earth and mars move in a circular orbit around the sun, with the martian orbit being `1.52` times the orbital radius of the Earth. What is the length of the martian year in days? `(G = 6.67 xx 10^(-11) Nm^(2) kg^(-2))`
Answer:
they have thin membranes to allow diffusion of substance for short distance
they are numerous to increase the surface area of absorption
hope this helps
All of the above should be the correct answer
