Answer:
Force, F = 187.42 N
Explanation:
It is given that,
Mass of boy, m = 30 kg
Acceleration due to gravity, 
Radius of curvature of the roller coaster, r = 15 m
Speed of the car, v = 7.3 m/s
The force acting on the boy are force of gravity and the centripetal force. The net force acting on him is as follows :



F = 187.42 N
So, he press against the seat with a force is 187.42 N. Hence, this is the required solution.
Suspect and mounts are a solid frame. True.
The number of protons in an atom is known as the atomic number
I don't think the shaping of the beach or hill would be considered
weathering, especially since it says "as smaller particles are moved
away". This one is just talking about where the particles decide to
gather and make a shape.
'C' is really talking about weathering, where rocks are broken up into
stones, and the stones into smaller pieces that can be blown away
on the wind. THAT's weathering.