Answer:
Explanation:
Cop of reversible refrigerator = TL / ( TH - TL)
TL = low temperature of freezer = 20 °F
TH = temperature of air around = 75 °F
Heat removal rate QL = 75 Btu/min
W actual, power input = 0.7 hp
conversion on F to kelvin = (T (°F) + 460 ) × 5 / 9
COP ( coefficient of performance) reversible = (20 + 460) × 5/9 / (5/9 ( ( 75 +460) - (20 + 460) ))
COP reversible = 480 / 55 = 8.73
irreversibility expression, I = W actual - W rev
COP r = QL / Wrev
W rev = QL / COP r where 75 Btu/min = 1.76856651 hp where W actual = 0.70 hp
a) W rev = 1.76856651 hp / 8.73 = 0.20258 hp is reversible power
I = W actual - W rev
b) I = 0.7 hp - 0.20258 hp = 0.4974 hp
c) the second-law efficiency of this freezer = W rev / W actual = 0.20258 hp / 0.7 hp = 0.2894 × 100 = 28.94 %
Answer:
the data are inadequate
Explanation:
<u>If there are 15 people on the team, and only five have been asked about the mascot, </u><u>this means the data collecting is wrong, and the result doesn’t include thoughts of the majority</u>. If Diana and Kinsey want to have adequate data,<u> they should ask as many as possible, if not all players in the team</u>. This would truly show what the majority wants meaning it will show what the team wants. This kind of complete data correcting is the correct one.
Answer:
stress = 8,556 Psi. or (stress = 59 Mpa)
Explanation:
stress = force / area
force P = 3 tons (convert to lbs. for units consistency)
1 ton = 2240 lbs.
P = 6,720 lbs.
steel bar Diameter D = 1 in. (convert to d
Area of steel bar = (π * 1²) / 4 = 0.785 in²
therefore, stress = 6720 lbs. / 0.785 in²
stress = 8,556 Psi.
in Mpa ----- 8556 Psi * 0.00689476 MPa/Psi = 59 Mpa
Acceleration of Car = 10 ms⁻²
Explanation:
Step 1:
The basic formula of acceleration is a = (v-u)/t ms⁻²
where, v- final velocity
u- initial velocity
t= time taken
Step 2:
Here v = 70 ms⁻¹
u = 50 ms⁻¹
t = 5 s
∴ a = ( 70 - 20)/5
a = 10 ms⁻²
