Humans hear frequencies from 20 Hz<span> (low) up to </span>20,000 Hz (high)
Answer:
Angle of incidence = 20°
Angle of reflection = 20°
Explanation:
Applying,
The first Law of Refraction: The incident ray, the reflected ray and the normal at the point of incidence all lies in the plane.
From the diagram,
Angle of incidence = 90-70
Angle of incidence = 20°
From the law of reflection,
Angle of incidence = Angle of reflection
Therefore,
Angle of reflection = 20°
A. IMA: 4
The Ideal Mechanical Advantage (IMA) is given by:

where
is the input distance
is the output distance
For the pulley system in this problem,
and
, so the IMA is

B. MA: 3.59
The actual mechanical advantage (AMA), or simply the Mechanical Advantage (MA), is given by

where
is the output force and
is the input force. For the pulley system in this problem,
and
, so the MA is

C. Efficiency: 89.8 %
The efficiency of a machine is equal to the ratio between the MA and the AMA:

Therefore, in this case,
