# phys

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An astronaut drops an object from rest (relative to the planet) on a planet alpha (having the same radius as of earth) from an altitude of one radius above the surface. When the object hits the surface its speed is 3.98 times what it would be if the same experiment were carried out for Earth. What is the mass of this planet?

• phys -

speed is 3.98

vf^2=2gd

3.98^2=g/9.8

well, g/9.8= Mp/Me
mp=me*3.98^2

check that.

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