Answer:
135 hour
Explanation:
It is given that a carburizing heat treatment of 15 hour will raise the carbon concentration by 0.35 wt% at a point of 2 mm from the surface.
We have to find the time necessary to achieve the same concentration at a 6 mm position.
we know that
where x is distance and t is time .As the temperature is constant so D will be also constant
So
then
we have given
and we have to find
putting all these value in equation

so
Answer:
If there is a shaft with headgear, then mining can take place until that depth of the shaft. If it is accessed horizontal Adits, it can mine until the lowest Adit from upwards. If it is accessed decline, the development and mining can continue so long as economic exploitation is possible.
Explanation:
What are the disadvantages of mining headgear? They totally cut off your vision of anything above your head. They are hot, most of the time
Answer:
35.7 kg lid we put
Explanation:
given data
temperature = 105 celcius
diameter = 15 cm
Patm = 101 kPa
to find out
How heavy a lid should you put
solution
we know Psaturated from table for temperature is 105 celcius is
Psat = 120.8 kPa
so
area will be here
area =
..................1
here d is diameter
put the value in equation 1
area =
area = 0.01767 m²
so net force is
Fnet = ( Psat - Patm ) × area
Fnet = ( 120.8 - 101 ) × 0.01767
Fnet = 0.3498 KN = 350 N
we know
Fnet = mg
mass = 
mass = 
mass = 35.7 kg
so 35.7 kg lid we put
Answer:
decreased
Explanation:
when impaired you react slower then you would sober.