The answer is C.
Ionic compounds are those that bring together anions and cations bonded together by ionic bonds. The electrostatic forces of the different charges are significant in the bonds that make them strong hence require high energy to break them (high melting point). Due to the regular structure of ionic compound that tend to form lattices in solid form, when struck, they shatter along the lines of weakness of the lattice.
Well, first of all, I don't think "After the collapse of a nebular cloud ..."
is the first time that "atoms begin gravitating together". Seems to me like
that's what was going on all the time, and it's what caused the nebular cloud
to collapse in the first place.
In any case, once the pressure and temperature at the center get high enough,
you get "ignition" of nuclear fusion, and that's when you first have a "star".
From the picture, I see that you had no trouble at all with #4.
Well, #5, 6, and 7 are easily handled in exactly the same way.
Just as you did with #4, please sketch these on paper
as I walk you through the solutions. That'll help you see
immediately what's going on.
#5.b).
Traveling east at 3 m/s for 4 seconds,
he covers (3 m/s) x (4 sec) = 12 meters.
Traveling south at 5 m/s for 2 seconds,
he covers (5 m/s) x (2 sec) = 10 meters.
The total distance he covers is (12m + 10m) = 22 meters.
#5.c).
Average speed (scalar)
= (distance covered)/(time to cover the distance)
= (22 meters)/(6 sec) = 3-2/3 m/s .
#5.d).
Displacement (vector)
= distance between the start-point and the end-point,
regardless of the route traveled,
in the direction from the start-point to the end-point.
Distance from the start-point to the end-point =
√(12² + 10²) = √(144 + 100) = √(244) = 15.62 meters
in the direction of arctan(10/12) south of east
= 39.8° south of east.
#5.e).
Average velocity (vector) =
(displacement vector) / (time)
= 15.62 meters directed 39.8° south of east / 6 seconds
= 2.603 m/s directed 39.8° south of east.
#6).
Magnitude = √(5.2² + 2.1²) = √(27.04 + 4.41) = √31.45 = 5.608 km.
Direction = arctan(5.2/2.1) south of east
= 68° south of east = 158° bearing .
#7).
Magnitude = √(39² + 57²) = √(1521 + 3249) = √( 4770)
= 69.07 m/s .
Direction = arctan (57/39) south of west
= 55.6° south of west
Bearing = 214.4°
Compass: 0.65° past "southwest by south".
I'm grateful for the privilege and opportunity to practice my math,
and I shall cherish the bounty of 5 points that came with it.
