Answer:
a) 

b) 
Explanation:
The net force on the car must produce the centripetal acceleration necessary to make this circle, which is  . At the top of the circle, the normal force and the weight point downwards (like the centripetal force should), while at the bottom the normal force points upwards (like the centripetal force should) and the weight downwards, so we have (taking the upwards direction as positive):
. At the top of the circle, the normal force and the weight point downwards (like the centripetal force should), while at the bottom the normal force points upwards (like the centripetal force should) and the weight downwards, so we have (taking the upwards direction as positive):

Which means:

The limit for falling off would be  , so the minimum speed would be:
, so the minimum speed would be:

 
        
             
        
        
        
Answer:
<em>It matters because crystalline and amorphous materials have different properties. The arrange affects the melting point (defined in crystals and a larger range in amorphous) and shape (geometrical in crystals, no geometrical in amorphous). </em>
Explanation:
The particles that compose a solid material are held in place by strong tractive forces between them when we analyze solids we consider the position of the atoms (molecules or ions) rather than their motion (which is important in liquids and gases). This positioning can be arranged in two general ways:
- Crystalline solids have internal structures that in turn lead to distinctive flat surfaces or face, these faces intersect at angles that are characteristic of the substance, crystals tend to have sharp, well defined and high melting points because of the same distance from the same number and type of neighbors. They generally have geometric shapes, some examples are diamonds, metals, salts.
- Amorphous solids produce irregular or curved surfaces when broken and they have poorly defined patterns when exposed to x rays because of their irregular array. In contrast with crystal solids, amorphous solids soften over a wide temperature range due to the different amounts of thermal energy needed to overcome different interactions. Some examples of these solids are gels, plastics, and some polymers.
I hope you find this information useful and interesting! Good luck!
 
        
             
        
        
        
Since it is dropped, initial velocity u = 0
Using s = ut + (1/2)gt^2,        putting u = 0,  g = 10 m/s^2
s =(1/2)gt^2,                  t = 3s
s = 0.5 * 10 * 3 *3
s = 45 m.
The bridge is 45m above the water.