It would mean that you could not know the precise volume of the sand. Only the volume of the sand plus the water that was making it damp. 
In the experiments listed, the effects are easy to deduce by understanding that the water in the sand adds volume to the 'sample' being measured. 
So in the case of calculating air space you would calculate <em>less</em> air space. 
        
             
        
        
        
It is because the effort distance is greater than the load distance
Explanation:
As we know, Effort×effort distance = load × load distance
So when effort distance is increases,
The effort decreases
So when the spanner’s handle is long
A tight knot can easily be opened by less effrot
I hope it helped
 
        
             
        
        
        
Answer:
The value is 
Explanation:
From the question we are told that 
 The diameter of the pupil is 
 The distance of the page from the eye 
 The wavelength is 
 The refractive index is 
Generally the minimum separation of adjacent dots that can be resolved is mathematically represented as 
 ![y  = [ \frac{1.22 *  \lambda }{d_p * n_r } ]* d](https://tex.z-dn.net/?f=y%20%20%3D%20%5B%20%5Cfrac%7B1.22%20%2A%20%20%5Clambda%20%7D%7Bd_p%20%2A%20n_r%20%7D%20%5D%2A%20d)
          ![y  = [ \frac{1.22 *  500 *10^{-9} }{4.2 *10^{-3} * 1.36} ]* 0.29](https://tex.z-dn.net/?f=y%20%20%3D%20%5B%20%5Cfrac%7B1.22%20%2A%20%20500%20%2A10%5E%7B-9%7D%20%7D%7B4.2%20%2A10%5E%7B-3%7D%20%2A%201.36%7D%20%5D%2A%200.29)
          
 
        
             
        
        
        
Answer
given,                            
mass of the piano = 170 kg              
angle of the inclination = 20°                 
moves with constant velocity hence acceleration = 0 m/s²    
neglecting friction                                   
so, force required to pull the piano                    
F = m g sin θ                                                      
F = 170 × 9.81 × sin 20°                                         
F = 570.39 N                                                    
so, force required by the man to push the piano is F = 570.39 N
 
        
             
        
        
        
answer:
heating the material
placing the material in a magnetic field of opposite polarity
hitting the material