Answer:

So then the answer for this case would be 29906 cal but we need to convert this into KJ and we know that 1 cal = 4.184 J and if we convert we got:

Explanation:
For this case we know the mass of the water given :

And we know that the initial temperature for this water is  .
.
We want to cool this water to the human body temperature 
Since the temperatures given are not near to 0C (fusion point) or 100C (the boling point) we don't need to use latent heat, then the only heat involved for this case is the sensible heat given by:

Where  represent the specific heat for the water and this value from tables we know that
 represent the specific heat for the water and this value from tables we know that  for the water.
 for the water. 
So then we have everything in order to replace into the formula of sensible heat and we got:

So then the answer for this case would be 29906 cal but we need to convert this into KJ and we know that 1 cal = 4.184 J and if we convert we got:

 
        
                    
             
        
        
        
Answer:
Nylon fibres
Explanation:
Nylon fibres are synthetic polymers made of repeating units linked by amide links. It is a thermoplastic silky material which can be remoulded in any shape.
Nylon fibres have the property of strong elastic and light in weight that is why used for making ropes,  combat uniforms, and parachutes. Nylon Fibres are also lustrous and easy to wash so widely used in textile industry for making swimwear, track pants, shorts, and draperies.
Hence, the correct answer is "Nylon fibres".
 
        
             
        
        
        
Answer:
Explanation:
Work is defined as the scalar product of force and distance 
W=F•d
Given that
 F = 8.5i + -8.5j. +×-=-
F=8.5i-8.5j
 d = 2.5i + cj
If the work in the practice is zero, then W=0
therefore,
W=F•ds
0=F•ds
0=(8.5i -8.5j)•(2.5i + cj)
Note that 
i.i=j.j=k.k=1
i.j=j.i=k.i=i.k=j.k=k.j=0
So applying this
0=(8.5i -8.5j)•(2.5i + cj)
0= (8.5×2.5i.i + 8.5×ci.j -8.5×2.5j.i-8.5×cj.j)
0=21.25-8.5c
Therefore,
8.5c=21.25
c=21.25/8.5
c=2.5
 
        
             
        
        
        
Answer:
Air is a mixture.
Explanation:
Air is a homogeneous mixture. It is made up of gaseous substances such as nitrogen, oxygen, and smaller amounts of others. 
Carbon dioxide is a pure substance, not a mixture. 
Carbon is another pure substance, it cannot be separated into other substances. 
Oxygen is just oxygen, it does not contain any other substance.