Answer: The normal force the rider experiences is the sum of the gravitational force acting on the rider and the friction force acting between the rider and the wall of the barrel.
Normal force = gravitational force + friction force
The gravitational force acting on the rider can be calculated using the weight of the rider, which is the mass of the rider multiplied by the acceleration due to gravity:
Weight = mass * acceleration due to gravity
Weight = 75 kg * 9.8 m/s^2 = 735 N
The friction force acting between the rider and the wall of the barrel can be calculated using the coefficient of friction and the normal force:
Friction force = coefficient of friction * normal force
Solving for the normal force, we get:
Normal force = Weight / (1-coefficient of friction) = 735 N / (1-0.5) = 1470 N
To find the minimum speed the ride can turn so that the rider doesn't slide down the wall, we can use the formula
velocity = square root of ( (Normal force * radius ) / (mass))
Minimum speed = √(1470 N * 4 m / 75 kg) = 14.5 m/s (round to the nearest tenth)