Answer:
Book. Bottle. table are some examples of objects in equilibrium found in classroom
 
 
        
             
        
        
        
Answer:
W = 12.96 J
Explanation:
The force acting in the direction of motion of the sand paper is the frictional force. So, we first calculate the frictional force:
F = μR
where,
F = Friction Force = ?
μ = 0.92
R = Normal Force = 2.6 N
Therefore,
F = (0.92)(2.6 N)
F = 2.4 N
Now, the displacement is given as:
d = (0.12 m)(45)
d = 5.4 m
So, the work done will be:
W = F d
W = (2.4 N)(5.4 m)
<u>W = 12.96 J</u>
 
        
             
        
        
        
Answer:
Refracted rays travel through a boundary into a new medium.
Explanation:
Refracted rays travel through a boundary into a new medium. is only true for refraction. 
The angle of incidence is the same for angle of refraction, is not true for refraction. Refraction follows Snell's law, states that ratio of the sine of the angle of refraction and the sine of the angle of incidence is always constant and equivalent to the ratio of phase velocities of the two mediums it is passing through. 
Refracted rays change direction and go back to the original medium is false for refraction however, it is true for reflection.