Explanation:
voltage, current and resistance are the Volt [ V ], Ampere [ A ] and Ohm [ Ω ]
Answer:
The efficiency of a DC generator is maximum when those losses proportional to the square of the load current are equal to the constant losses of the DC generator. This relation applies equally well to all rotating machines, regardless of the type of machine.
Explanation:
Answer:
a) omax=125 MPa
omin=75 MPa
b) Temperature = 1289.6°F
Explanation:
a) The mean stress is:
omax+omin=200 MPa
stress amplitude=50 MPa
omax-omin=50MPa
2omax=250 MPa
omax=125 MPa
omin=75 MPa
b) For copper, the creep is important at 0.65 of the melting point, thus:
Temperature = 0.65*1984°F=1289.6°F
Answer:
T=833.8 °C
Explanation:
Given that
m= 2 kg
T₁=200 °C
time ,t= 10 min = 600 s
Work input = 1 KW
Work input = 1 x 600 KJ=600 KJ
Heat input = 0.5 KW
Q= 05 x 600 = 300 KJ
Gas is ideal gas.
We know that for ideal gas internal energy change given as
ΔU= m Cv ΔT
For air Cv= 0.71 KJ/kgK
From first law of thermodynamics
Q = ΔU +W
Heat input taken as positive and work in put taken as negative.
300 KJ = - 600 KJ + ΔU
ΔU = 900 KJ
ΔU= m Cv ΔT
900 KJ = 2 x 0.71 x (T- 200 )
T=833.8 °C
So the final temperature is T=833.8 °C