- #1

Lord Anoobis

- 131

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## Homework Statement

A 1.0kg object is released form rest 500km above the earth. What is its impact speed as it hits the ground? Ignore air resistance.

## Homework Equations

##U_g = \frac{GmM_e}{r}##

##K = \frac{1}{2}mv^2##

## \Delta U = - \Delta K##

## The Attempt at a Solution

Using energy conservation I arrived at

##\frac{GmM_e}{r} = \frac{1}{2}mv^2##, then ##v = sqrt{\frac{2GM_e}{r}}##

Plugging in values, ##v = \sqrt{\frac{2(6.67\times10^{-11})(5.98\times10^{24})}{(6.37\times10^6 +5.00\times10^5)}} = 10776 m/s##, never mind the significant figures.

This is rather far from the correct answer though, which is 3.02km/s.