Answer:
It's an Angle of incidence that provides a 90° angle but is also refracted at the same time. it's used to find the water-air boundary (which is 48.6 degrees). in addition, its an angle of incidence value.
I would say C i'm not 100% sure
Answer:
Max speed = 
Max acceleration = 
Explanation:
Given the description of period and amplitude, the SHM could be described by:

and its angular velocity can be calculated doing the derivative:

And therefore, the tangential velocity is calculated by multiplying this expression times the radius of the movement (3 m):
and is given in m/s.
Then the maximum speed is obtained when the cosine function becomes "1", and that gives:
Max speed = 
The acceleration is found from the derivative of the velocity expression, and therefore given by:

and the maximum of the function will be obtained when the sine expression becomes "-1", which will render:
Max acceleration = 
Answer: 2.2x10^4
Explanation: in a adiabatic process pV^y = constant.
So V2=3V1 and p2 = p1 / 3^1.67 = 2.2x10^4 Pa