Question 1
Show that the orbital speed of a planet is constant if and only if the orbit is circular.
Question 2
Write the equation for the surface obtained by revolving the curve z = y
2 (in the yz-plane) about the z-axis.
◦ z = x
2 + y
2◦ z = x + y
2◦ z = x
2 - y
2◦ z = - x
2 - y
2◦ z = - x
2 + y
2