mechanics 2 (urgent)

1. The astronaut feels weightlessness is because he has no relative motion with the orbiting satellite. It is because both the astronaut and satellite are in the same orbit revolving round the earth.

2. A parking orbit must be a circular orbit over the equator such that the angular speed of the revolving satellite is the same as that of the earth. The speed of satellite in an elliptical orbit is not constant, but varies along the orbit.

3. The "normal" is an axis passing through the plane of the station. It forms the axis of rotation of the station.

4. You cannot just pick two points and calculate the slope. With the given data, you should plot a graph of w^2 gainst 1/cos(theta), or cos(theta) against 1/w^2 as you like. Find the slope from the plotted graph.

2011-09-04 00:55:18 補充：
3. Your drawing is wrong. The atronanut should have his feet on the outside and his hear on the inside. It is because the "artificial gravity" comes from the centrifugal force arising from the rotation of the space station. ...

2011-09-04 00:55:36 補充：
.... The centrifugal force tends to pull the astronaut away from the axis of rotation.

2011-09-04 09:33:54 補充：
Suupl Q:1. There is no place in the universe where gravity is zero, because gravitational force extends to infinity. A person feels "weight" when he is pressed by a force onto a surface. If no such surface exist, he does not feel any weight.

2011-09-04 09:37:14 補充：
Suppl Q2: Both. Satellite orbits can be circular or elliptical depending on the speedof the satellite and the angle at which the satellite enters into orbit.

2011-09-04 09:44:16 補充：
Suppl Q3: you cannot take any two points to calculate the slope. You have to plot the graph to find the best fitted line, and calculate the slope from the plotted line. The difference between the two answers is clearly due to deviation of the points from the best fitted line.