Rockfalls can cause major damage to roads and infrastructure. To design mitigation bridges and barriers, engineers use the coeff
icient of restitution to model the behavior of the rocks. The rock A falls a distance of 32 m before striking an incline with slope α = 40°. Knowing that the coefficient of restitution between A and the incline is 0.2, determine the velocity of the rock after the impact.
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Answer:
A) W' = 15680 KW
B) W' = 17113.87 KW
Explanation:
We are given;
Temperature at state 1; T1 = 290 K
Temperature at state 3; T3 = 1100 K
Rate of heat transfer; Q_in = 35000 kJ/s = 35000 Kw
Pressure of air into compressor; P_c = 95 kPa
Pressure of air into turbine; P_t = 760 kPa
A) The power assuming constant specific heats at room temperature is gotten from;
W' = [1 - ((T4 - T1)/(T3 - T2))] × Q_in
Now, we don't have T4 and T2 but they can be gotten from;
T4 = [T3 × (r_p)^((1 - k)/k)]
T2 = [T1 × (r_p)^((k - 1)/k)]
r_p = P_t/P_c
r_p = 760/95
r_p = 8
Also,k which is specific heat capacity of air has a constant value of 1.4
Thus;
Plugging in the relevant values, we have;
T4 = [(1100 × (8^((1 - 1.4)/1.4)]
T4 = 607.25 K
T2 = [290 × (8^((1.4 - 1)/1.4)]
T2 = 525.32 K
Thus;
W' = [1 - ((607.25 - 290)/(1100 - 525.32))] × 35000
W' = 0.448 × 35000
W' = 15680 KW
B) The power accounting for the variation of specific heats with temperature is given by;
W' = [1 - ((h4 - h1)/(h3 - h2))] × Q_in
From the table attached, we have the following;
At temperature of 607.25 K and by interpolation; h4 = 614.64 KJ/K
At T3 = 1100 K, h3 = 1161.07 KJ/K
At T1 = 290 K, h1 = 290.16 KJ/K
At T2 = 525.32 K, and by interpolation, h2 = 526.12 KJ/K
Thus;
W' = [1 - ((614.64 - 290.16)/(1161.07 - 526.12))] × 35000
W' = 17113.87 KW
Answer: Hello the question is incomplete below is the missing part
Question: determine the temperature, in °R, at the exit
answer:
T2= 569.62°R
Explanation:
T1 = 540°R
V2 = 600 ft/s
V1 = 60 ft/s
h1 = 129.0613 ( value gotten from Ideal gas property-air table )
<em>first step : calculate the value of h2 using the equation below </em>
assuming no work is done ( potential energy is ignored )
h2 = [ h1 + ( V2^2 - V1^2 ) / 2 ] * 1 / 32.2 * 1 / 778
∴ h2 = 136.17 Btu/Ibm
From Table A-17
we will apply interpolation
attached below is the remaining part of the solution
