- #1

rickyjoepr

- 6

- 1

## Homework Statement

A saucer of mass 1.75x10^9 enters

1.the gravitational field of PlanetX and enters its atmosphere; the gravitational field of the planet is 10.6 m/s2 and is considered uniform throughout the 80-km thick atmosphere.

If the saucer enters the atmosphere at 460 m/s and slows down to 110 m/s before its crash-landing, what is the average magnitude of the drag force (gravity cannot be neglected)?

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## Homework Equations

drag for disk, D = (1/4) AV^2

W = Total Mechanical Energy

## The Attempt at a Solution

E1 = (1/2)m1Vi^2 + mgd

E2 = 0 + 0

So W = (1/2)m1V1+mgd

Because W = Fd

W/d = F

2.55 x10^10

However the correct answer is listed as 2.07 x 10^10 N

I am not sure if my method of using mechanical energy is correct., Or wether I should be using the drag force equation to solve the problem