Represent the unknowns.
<span>Let x = length </span>
<span>since the width is 3/4 of the length, </span>
<span>Let (3/4)x = width </span>
<span>Recall that the area of rectangle is just width multiplied by the length, </span>
<span>A = w * l </span>
<span>Substituting, </span>
<span>432 = (3/4)x * x </span>
<span>432 = (3/4)x^2 </span>
<span>432 * 4/3 = x^2 </span>
<span>576 = x^2 </span>
<span>Get the square root of both sides, </span>
<span>x = 24 feet (length) </span>
Answer:
Step-by-step explanation:
Explanation:
First, multiply each side of the equation by
2
to eliminate the fraction while keeping the equation balanced:
2
×
A
=
2
×
h
2
(
a
+
b
)
2
A
=
2
×
h
2
(
a
+
b
)
2
A
=
h
(
a
+
b
)
Now, divide each side of the equation by
a
+
b
to solve for
h
while keeping the equation balanced:
2
A
a
+
b
=
h
(
a
+
b
)
a
+
b
2
A
a
+
b
=
h
(
a
+
b
)
a
+
b
2
A
a
+
b
=
h
h
=
2
A
a
+
b
Plug in -1 for x
and you'll get this:
Solve it further and you'll get:
Therefore,
where x = -1
Answer: Heat rejected=150000MW
Heat rate= 2.5
Step-by-step explanation:
Thermal efficiency is defined as work out divided by heat in.
Therefore
thermal efficiency = 40/100= 100000 MW/Heat in
Heat in = 250000MW
For a closed system undergoing a cycle the change in internal energy is zero. Therefore the work out of the system is equal to the net heat transfer of the system. Therefore
Work out= heat in - heat out
Therefore heat out = heat in - work out
Heat out = 250000 MW - 100000MW = 150000 MW which is the amount of heat rejected
The heat rate is defined as the inverse of the thermal efficiency expressed in kJ/kWh.Therefore
Heat rate = 1/thermal efficiency
Heat rate = 1/0.4 = 2.5 kJ/kWh
