Because other scientists and science in general rely on their collegues' research which in turn allows development of our knowledge on the given subject. The more dont-to-earth reason may be safety. If someone performs an experiment without knowledge of its true results it might result in some danger to the safety of those perforning it without knowledge of all the risks.
        
             
        
        
        
I believe it isa  refraction. hope this helps
        
                    
             
        
        
        
Answer:
400 trips
Explanation:
Mechanical energy needed to climb 14 m by a man of 68 kg 
= mgh 
= 68 x 9.8 x 14 
= 9330 J 
1 Kg of fat releases 3.77 x 10⁷ J of energy
.45 kg of fat releases 1.6965 x 10⁷ J of energy
22% is converted into mechanical energy
so 22% of 1.6965 x 10⁷ J 
= 3732.3 x 10³ J of mechanical energy will be available for mechanical work. 
one trip of climbing of 14 m requires 9330 J of mechanical energy
no of such trip possible with given mechanical energy 
= 3732.3 x 10³ / 9330
= 400 trips
 
        
             
        
        
        
Answer:
a much larger slit, the phenomenon of Sound diffraction that slits for light.
this is a series of equally spaced lines giving a diffraction envelope
Explanation:
The diffraction phenomenon is described by the expression
     d sin θ = m λ
Where d is the distance of the slit, m the order of diffraction that is an integer and λ the wavelength.
  
For train the diffraction phenomenon, the d / Lam ratio is decisive if this relation of the gap separation in much greater than the wavelength does not reduce the diffraction phenomenon but the phenomena of geometric optics.
 The wavelength range for visible light is 4 10⁻⁷ m to 7 10⁻⁷ m. The wavelength range for sound is 17 m to 1.7 10⁻² m. Therefore, with a much larger slit, the phenomenon of Sound diffraction that slits for light.
When we add a second slit we have the diffraction of each one separated by the distance between them, when the integrals are made we arrive at the result of the interference phenomenon, a this is a series of equally spaced lines giving a diffraction envelope
 When I separate the distance between the two slits a lot, the time comes when we see two individual diffraction patterns