Answer:
Removing some of the books reduced the mass of the box, and less force was needed to push it across the floor.
The best choice would be letter C hope this helps
To solve this problem we will apply the concepts related to Reyleigh's criteria. Here the resolution of the eye is defined as 1.22 times the wavelength over the diameter of the eye. Mathematically this is,

Here,
D is diameter of the eye


The angle that relates the distance between the lights and the distance to the lamp is given by,

For small angle, 
Here,
d = Distance between lights
L = Distance from eye to lamp
For small angle 
Therefore,



Therefore the distance is 5.367km.
Answer:
The structure of Germanium crystals will be destroyed at higher temperature. However, Silicon crystals are not easily damaged by excess heat. Peak Inverse Voltage ratings of Silicon diodes are greater than Germanium diodes. Si is less expensive due to the greater abundance of element.
Friction
Friction also affects the movement of an object on a slope. Friction is a force that offers resistance to movement when one object is in contact with another. Imagine now that you were on the downside of the object and applying force to keep the object in the same place (not moving)