Answer:
Correct option a) True.
Explanation:
It is true since the Vickers hardness value refers to the force applied in a 136 ° diamond tip penetrator divided by the surface of the groove produced in the material, the lower the impression made on this greater the value will be end of the Vickers measurement and greater its hardness.
The equation to determine the Vickers hardness value will be:
Hv= ((1.854 × P)/(d²)) (kg/mm²)
Therefore a value of 220 Vickers refers to a harder material than another value of 180 Vickers.
Answer:
Q = 63,827.5 W
Explanation:
Given:-
- The dimensions of plate A = ( 10 mm x 1 m )
- The fluid comes at T_sat , 1 atm.
- The surface temperature, T_s = 75°C
Find:-
Determine the total condensation rate of water vapor onto the front surface of a vertical plate
Solution:-
- Assuming drop-wise condensation the heat transfer coefficient for water is given by Griffith's empirical relation for T_sat = 100°C.
h = 255,310 W /m^2.K
- The rate of condensation (Q) is given by Newton's cooling law:
Q = h*As*( T_sat - Ts )
Q = (255,310)*( 0.01*1)*( 100 - 75 )
Q = 63,827.5 W
The answer would be letter A
Answer:
The pressure difference across hatch of the submarine is 3217.68 kpa.
Explanation:
Gauge pressure is the pressure above the atmospheric pressure. If we consider gauge pressure for finding pressure differential then no need to consider atmospheric pressure as they will cancel out. According to hydrostatic law, pressure varies in the z direction only.
Given:
Height of the hatch is 320 m
Surface gravity of the sea water is 1.025.
Density of water 1000 kg/m³.
Calculation:
Step1
Density of sea water is calculated as follows:

Here, density of sea water is
, surface gravity is S.G and density of water is
.
Substitute all the values in the above equation as follows:


kg/m³.
Step2
Difference in pressure is calculated as follows:


pa.
Or

kpa.
Thus, the pressure difference across hatch of the submarine is 3217.68 kpa.
Answer:
minimum electric power consumption of the fan motor is 0.1437 Btu/s
Explanation:
given data
area = 3 ft by 3 ft
air density = 0.075 lbm/ft³
to find out
minimum electric power consumption of the fan motor
solution
we know that energy balance equation that is express as
E in - E out =
......................1
and at steady state
= 0
so we can say from equation 1
E in = E out
so
minimum power required is
E in = W = m
=
put here value
E in =
E in =
E in = 0.1437 Btu/s
minimum electric power consumption of the fan motor is 0.1437 Btu/s