- #1

- 53

- 0

50kmh-1 = 13.9 m/s

v=sqrt(2GM/r)

G=6.67 x 10^-11

M=5.98 x 10^24

r=???

13.9=sqrt(7.98 x 10^14/r)

193.21=7.98 x 10^14/r

193.21r=7.98 x 10^14

r=7.98 x 10^14/193.21

r=4.13 x 10^12

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- Thread starter warmfire540
- Start date

- #1

- 53

- 0

50kmh-1 = 13.9 m/s

v=sqrt(2GM/r)

G=6.67 x 10^-11

M=5.98 x 10^24

r=???

13.9=sqrt(7.98 x 10^14/r)

193.21=7.98 x 10^14/r

193.21r=7.98 x 10^14

r=7.98 x 10^14/193.21

r=4.13 x 10^12

- #2

G01

Homework Helper

Gold Member

- 2,665

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Looks good to me. Any specific question?

- #3

alphysicist

Homework Helper

- 2,238

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Are you sure you copied the problem down correctly? I can see where it doesn't seem right to you--the problem indicates that the radius you solve for should be smaller than the earth's radius, but the one you calculate is much larger.

Did you copy the given escape speed correctly? Could it have supposed to have been something like 50000 km/hour? The real escape speed of the earth is around 40000 km/hour, and if we want the radius to be smaller we need the given speed to be larger.

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