# Calculate orbital angular momentum

• ssarpal
In summary, the section Kepler’s Second Law discusses the equation r = D, m = M, and v = V and how to find the value of theta in Figure 13.21. However, it is not possible to find theta unless the satellite is at apogee or perigee.

#### ssarpal

Homework Statement
A satellite of mass M kgs has an elliptical orbit of T hours around the Earth with ##Rmax = N * Rmin##.
At one instant, the satellite is at a distance D meters from center of Earth and moving at V km/s.

Q) Find the orbital angular momentum.
Relevant Equations
L = r * m * v * sin θ
The section Kepler’s Second Law here describes the above equation.

In this problem,
##\text{r = D, m = M and v = V}##

What is the way to go about finding out ##\theta## as shown in Figure 13.21?

Perhaps trying to find ##\theta## isn't the way to go. Any other ideas?

ssarpal said:
At one instant, the satellite is at a distance D meters from center of Earth and moving at V km/s.
As you seem to have discovered, this cannot be be solved unless the "one instant" is known to be at one of the orbital extremes (apogee or perigee). Then you would naturally know ##\sin \theta##.