b is your answers in this thread 
 
        
             
        
        
        
Answer:

Explanation:
An object is at rest along a slope if the net force acting on it is zero. The equation of the forces along the direction parallel to the slope is:
 (1)
 (1)
where
 is the component of the weight parallel to the slope, with m being the mass of the object, g the acceleration of gravity,
 is the component of the weight parallel to the slope, with m being the mass of the object, g the acceleration of gravity,  the angle of the slope
 the angle of the slope
 is the frictional force, with
 is the frictional force, with  being the coefficient of friction and R the normal reaction of the incline
 being the coefficient of friction and R the normal reaction of the incline
The equation of the forces along the direction perpendicular to the slope is

where
R is the normal reaction
 is the component of the weight perpendicular to the slope
 is the component of the weight perpendicular to the slope
Solving for R,

And substituting into (1)

Re-arranging the equation,

This the condition at which the equilibrium holds: when the tangent of the angle becomes larger than the value of  , the force of friction is no longer able to balance the component of the weight parallel to the slope, and so the object starts sliding down.
, the force of friction is no longer able to balance the component of the weight parallel to the slope, and so the object starts sliding down.
 
        
             
        
        
        
The resistance between A and B is 10 ohms.
        
             
        
        
        
<span><em>78% = nitrogen</em>
<em>21% = oxygen</em>
</span>
<em>%1  = noble gases</em>