Answer:cross-sectional area, and thus surface area, increases the amount of air resistance an object experiences
Explanation:
 
        
             
        
        
        
Answer:
The value of the average convection coefficient is 20 W/Km².
Explanation:
Given that,
For first object,
Characteristic length = 0.5 m
Surface temperature = 400 K
Atmospheric temperature = 300 K
Velocity = 25 m/s
Air velocity = 5 m/s
Characteristic length of second object = 2.5 m
We have same shape and density of both objects so the reynold number will be same,
We need to calculate the value of the average convection coefficient
Using formula of  reynold number for both objects



Here, 


Put the value into the formula


Hence, The value of the average convection coefficient is 20 W/Km².
 
        
             
        
        
        
Answer:
In a velocity selector, there are two forces namely;
» Electric field Intensity
» Magnetic field density
<u>Relationship</u><u>:</u>

E is the electric field intensity
B is the magnetic flux density
 
        
             
        
        
        
Nitrogen is the most abundant of the gases present in the atmosphere. 78 percent of the atmospheric air comprises of nitrogen, oxygen makes up for 21 percent and all other gases make up for the remaining one percent. Oxygen is a highly flammable gas and in the absence of nitrogen it would not have been possible to utilize this atmospheric oxygen, hence the presence of nitrogen reduces its flammability and also neutralizes the toxicity of other gases.