The transition from gas to liquid is called condensation. An example would be water droplets forming on an ice cold glass placed in room temperature.
D because friction will slow it down going up hills (for safety reasons) and you go really fast going down.
Answer:
An equipotential surface is circular in the two-dimensional. Since the electric field lines are directed radially away from the charge, hence they are opposite to the equipotential lines. Therefore, the electric field is perpendicular to the equipotential surface.
Astronomers can measure a star's position once, and then again 6 months later and calculate the apparent change in position. The star's apparent motion is called stellar parallax. The distance d is measured in parsecs and the parallax angle p is measured in arcseconds.
I hope this helps!