# Age of the Nebula

The gas shell of a planetary nebula is expanding (away from the central star) at 20 km/s. The nebula currently has a diameter of 1 light year. What is the age of the planetary nebula(time since the gas was ejected)?

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#### Solution Preview

This problem uses the basic formula relating velocity, distance and time

v = d / t or, for this problem, t = d / v.

What is moving in this problem is the outer layers of the ...

#### Solution Summary

This solution computes the age of the nebula.

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