A real cubic expansivity is an increase in the volume of a liquid per unit volume per degree rise in temperature when heated in an inexpansible vessel.
A surface wave is a wave in which particles of the medium undergo a circular motion.
Answer: because they have equal numbers of protons
Explanation: Atoms are electrically neutral because they have equal numbers of protons (positively charged) and electrons (negatively charged). If an atom gains or loses one or more electrons, it becomes an ion
1) 3 miles/Hour
The speed is defined as the distance covered divided by the time taken:

where
d = 1.5 mi is the distance
t = 0.5 h is the time taken
Substituting,

2) 1.34 m/s south
Velocity, instead, is a vector, so it has both a magnitude and a direction. We have:
is the displacement in meters
is the time taken in seconds
Substituting,

And the direction of the velocity is the same as the displacement, so it is south.