Answer:
1) q=18414.93 W
2) C=12920$
Explanation:
Given data:
pipe length L=25m
pipe diameter D=100mm =0.1 m
air temperature 
=
=25
°C.....= 298.15k
pipe surface temp 
=150
°C.....=423.15k
surface emissivity e= 0.8
boiler efficiency η=0.90
natural gas price Cg=$0.02 per MJ
1) Total heat loss and radiation heat loss combined
q=
q=
б(^4-^4)]....... (1)
б=5.67×10^-8 W/m^2K^4 (boltzmann constant)
area A =L.Dπ=25×0.1π=7.85 m^2
putting all these values in eq (1)
q=18414.93 W
2) suppose boiler is operating non stop annual energy loss will be
E=q.t
=18414.93.3600.24.365
=5.81×10^11 J
to find furnace energy consumption
Ef =E/η
=6.46×10^5 MJ
annual cost
C=Cg. Ef
=12920$
Answer:
Option C
Both A and B
Explanation:
Both technicians are right about what they say about wire brushes. wire brushes are usually made up of steel wire bristles. however, when high RPMs are involved, it is better to get some special types of brushes for that purpose. This is because the heat generated at high RPMs is great, and most times, damages the brush after prolonged use if it is not specially built for such speeds.
In addition that, some wire brushes have plastic hubs which help support the bristles and is usually attached to the motor.
Considering these, we can say that the Two technicians are right
Answer:
1/6
Explanation:
A dice has 6 sides, the probability of 4 appearing is 1/6.
Answer:
a)Wt =25.68 lbf
b)Wt = 150 lbf
F= 899.59 N
Explanation:
Given that
m= 150 lbm
a)
Weight on the spring scale(Wt) = m g
We know that
Wt = 150 x 5.48/32 lbf
Wt =25.68 lbf
b)
On the beam scale
This is scale which does not affects by gravitational acceleration.So the wight on the beam scale will be 150 lbf.
Wt = 150 lbf
If the plane is moving upward with acceleration 6 g's then the for F
F = m a
We know that
a=6 g's
So
F = 90 x 9.99 N
F= 899.59 N
