I think it is D
Hope my answer help you?
Answers:
a) 
b) 
c) 
Explanation:
<h3>a) Mass of the continent</h3>
Density
is defined as a relation between mass
and volume
:
(1)
Where:
is the average density of the continent
is the mass of the continent
is the volume of the continent, which can be estimated is we assume it as a a slab of rock 5300 km on a side and 37 km deep:

Finding the mass:
(2)
(3)
(4) This is the mass of the continent
<h3>b) Kinetic energy of the continent</h3>
Kinetic energy
is given by the following equation:
(5)
Where:
is the mass of the continent
is the velocity of the continent
(6)
(7) This is the kinetic energy of the continent
<h3>c) Speed of the jogger</h3>
If we have a jogger with mass
and the same kinetic energy as that of the continent
, we can find its velocity by isolating
from (5):
(6)
Finally:
This is the speed of the jogger
Well, there would have to major supports on every building that was tall even though we have very strong foundation the foundation doesn't do anything except no give us dirt as a floor.but a really strong structure to use is a triangle formation.
Hope this helped
Answer:
a. It always points perpendicular to the contact surface.
Explanation:
"Normal" means perpendicular. Normal forces are always perpendicular to the contact surface.
A and C Im pretty sure :)