If you drop a feather and a steel hammer at the same moment, they should hit the ground at the same instant. Why doesn’t this work on Earth, and why does it work on the Moon? Will it work on Phobos, a moon of Mars?

The reason the feather and the steel hammer do not fall at the same rate on Earth is due to the effect of air resistance. When an object falls through the Earth's atmosphere, it encounters air molecules that push against it, slowing it down. This resistance is more significant for objects with a larger surface area, like feathers, compared to denser objects like steel hammers. Hence, a feather experiences more air resistance and falls more slowly, while a steel hammer falls relatively faster.

On the Moon, however, there is no substantial atmosphere to provide resistance. Therefore, objects fall at the same rate regardless of their mass or size. Without air resistance, the feather and the steel hammer will hit the surface of the Moon simultaneously if released at the same time and from the same height.

As for Phobos, one of Mars' moons, the answer depends on whether Phobos has an atmosphere. If Phobos has a very thin atmosphere or no atmosphere at all, like the Moon, then the feather and the steel hammer would fall at the same rate. However, if Phobos possesses a dense atmosphere, then air resistance will come into play, causing the objects to fall at different rates, similar to what happens on Earth.

To determine if Phobos has an atmosphere, you may refer to scientific studies, research papers, or missions that have investigated its composition and atmospheric conditions. By examining the available information, you can discern whether the feather and the steel hammer would fall at the same rate on Phobos.

Read this, then tell us what you think.

http://science.howstuffworks.com/environmental/earth/geophysics/question232.htm