Answer:
you need to consider the use for the product, how brittle the materials are, how they react to certain things, the cost of the materials, the durability and flexibility of the materials, and how easy to obtain the materials are as well as how they would work and how they would hold
 
        
             
        
        
        
Answer:
Check explanation
Explanation:
In the formation of calcium fluoride we take calcium and fluorine.
in elemental form calcium exist in solid form and fluorine in gaseous form.
formation of compound takes place to complete their octet, in case of calcium  need to remove two electron and need to add one elecron in fluorine to complete their octet so two electron will ransferred from calcium to two fluorine atom.  
 
        
             
        
        
        
Given:
The magnitude of each charge is q1 = q2 = 1 C
The distance between them is r = 1 m
To find the force when distance is doubled.
Explanation:
The new distance is 

The force can be calculated by the formula

Here, k is the constant whose value is 

On substituting the values, the force will be

 
 
        
             
        
        
        
Answer:
 v = 3.04 m/s
Explanation:
given,
mass of the block, M = 6.6 Kg
horizontal force, F = 12.2 N
distance, L = 2.5 m
initial speed  = 0 m/s
speed of the block,v = ?
we now 
Work done is equal to change in Kinetic energy.
Work done = Force x displacement
W = Δ K E
Δ K E = Force x displacement


  3.3 v² = 30.5
      v² = 9.242
       v = 3.04 m/s
speed of the block is equal to 3.04 m/s