To determine the magnitude of the force you experience from the seat at the highest point of the Ferris wheel, we need to consider the forces acting on you. At the highest point of the Ferris wheel, two forces act on you: the force of gravity pulling you downward and the normal force from the seat pushing you upward.
The magnitude of the force of gravity pulling you downward is given by:
F_gravity = m * g
where m is your mass and g is the acceleration due to gravity, which is approximately 9.81 m/s^2 on Earth.
So, F_gravity = 80 kg * 9.81 m/s^2 = 784.8 N
At the highest point of the Ferris wheel, you are not accelerating vertically, so the net force on you in the vertical direction must be zero. This means that the magnitude of the normal force from the seat pushing you upward must be equal and opposite to the magnitude of the force of gravity pulling you downward.
Therefore, the magnitude of the normal force from the seat pushing you upward is also 784.8 N.
Note that the mass of the car is not needed to determine the magnitude of the force you experience from the seat.