**Problem : **
What is the escape velocity from the earth? (*M*_{e} = 5.98×10^{24} kilograms, *r*_{e} = 6.38×10^{6} meters)

v = = 1.12×10^{4}m/s |

Thus the escape velocity from the earth is roughly 11.2 kilometers per second.

**Problem : **
If a black hole contains a singularity (all the mass is concentrated at
a point) with a mass 1000 times the mass of the sun, what is the radius
beyond which light cannot escape? This is called the Schwartzchild
radius. The mass of the sun is 1.99×10^{30} kilograms and the
speed of light is 3×10^{8} m/s.

**Problem : **
We would expect a satellite orbiting the earth to be slowed down by
friction with the atmosphere. We also know that velocity is inversely
proportional to the radius of the orbit, so when the satellite slows
down, it should spiral away from the earth. But it is observed that
satellites spiral in towards the earth. How can we explain this
paradox?

**Problem : **
Suppose the viscous drag causes a 2000 kilogram satellite to increase
its speed from 10000 m/s to 15000
m/s. If the satellite had an initial orbital radius of 6.6×10^{3} kilometers, what is its new orbital
radius? (*M*_{e} = 5.98×10^{24} kilograms).

**Problem : **
At a height of 2×10^{7} meters above the center of the earth,
three satellites are ejected from a space
shuttle. They are given tangential speeds of 5.47 kilometers/sec, 4.47
km/sec, and 3.47 km/sec
respectively. Which one(s) will assume circular orbits? Which
elliptical? The mass of the earth is 5.98×10^{24} kilograms.

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