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.
Answer:
reduced
Explanation:
The use of bearing surfaces that are themselves sacrificial, such as low shear materials, of which lead/copper journal bearings are an example
Guess I recommend doing that
Answer:
60 kg m/s
Explanation:
Let
be the acceleration of the object.
As the acceleration of the object is constant, so

Given that applied force, F=6.00 N,
From Newton's second law, we have
,
[from equation (i)]


[given that time, t=10 s and F=6 N]

Here mv is the final momentum of the object and mu is the initial momentum of the object.
So, the change in the momentum of the object is mv-mu.
Hence, the change in the momentum of the object is 60 kg m/s.
I believe the answer is up and down :)