Final answer:
The angle at which the face of the wave is inclined above the horizontal is approximately 21.5°.
Step-by-step explanation:
The surfer's acceleration is 3.50 m/s² and friction can be ignored. To find the angle at which the face of the wave is inclined above the horizontal, we can use the formula:
a|| = g * sin(θ)
Where a|| is the acceleration parallel to the incline, g is the acceleration due to gravity (approximately 9.8 m/s²), and θ is the angle of the incline.
In this case, a|| = 3.50 m/s². Rearranging the formula, we get:
sin(θ) = a|| / g
Substituting the given values, we have:
sin(θ) = 3.50 / 9.8
θ = arcsin(3.50 / 9.8)
Using a calculator, we find that θ is approximately 21.5°.