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3 years ago

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A has a mass of 7 kg, object B has a mass of 5 lbm, and object C has a mass of 0.5 slug. (a) Which object has the largest mass?

Which object has the smallest mass? (b) Find the weights of objects A, B and C (in both N and lbf) on the surface of Mars.

1 answer:

ankoles [38]3 years ago

6 0

Answer:

1) Object C has the largest mass.

2)Object has the smallest mass.

3) Weight of A = 26.6 Newtons

4)Weight of B = 8.6184 Newtons

5)Weight of C = 27.7286 Newtons

Explanation:

Since all the given masses have different unit's we shall convert them all into a same base unit for comparison. The base unit is selected to be kilogram.

Hence

1) Mass of object A = 7 kilogram

2) Mass of object B = 5 pounds

We know that 1 pound equals 0.4536 kilograms Hence 5 pounds equals

$0.4536\times 5=2.268kg$

3) Mass of object C = 0.5 slug

We know that 1 slug equals 14.594 kilograms Hence 0.5 slug equals

$14.594\times 0.5=7.297kg$

Upon comparing all the 3 masses we conclude that object C has the largest mass and object B has the smallest mass.

Part b)

Weight of an object is given by

$Weight=mass\times g$

Now on Mars value of g equals $3.8m/s^{2}$

Thus the corresponding weights are as under:

$W_{A}=3.8\times 7=26.6N\\\\W_{B}=3.8\times 2.268=8.6184N\\\\W_{C}=3.8\times 7.297=27.7286N\\\\$

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Answer:

the net work per cycle $\mathbf{W_{net} = 0.777593696}$ Btu per cycle

the power developed by the engine, W = 88.0144746 hp

Explanation:

the information given includes;

diameter of the four-cylinder bore = 3.7 in

length of the stroke = 3.4 in

The clearance volume = 16% = 0.16

The cylindrical volume $V_2 = 0.16 V_1$

the crankshaft N rotates at a speed of 2400 RPM.

At the beginning of the compression , temperature $T_1$ = 60 F = 519.67 R

and;

Otto cycle with a pressure = 14.5 lbf/in² = (14.5 × 144 ) lb/ft²

= 2088 lb/ft²

The maximum temperature in the cycle is 5200 R

From the given information; the change in volume is:

$V_1-V_2 = \dfrac{\pi}{4}D^2L$

$V_1-0.16V_1= \dfrac{\pi}{4}(3.7)^2(3.4)$

$V_1-0.16V_1= 36.55714291$

$0.84 V_1 =36.55714291$

$V_1 =\dfrac{36.55714291}{0.84 }$

$V_1 =43.52040823 \ in^3 \\ \\ V_1 = 43.52 \ in^3$

$V_1 = 0.02518 \ ft^3$

the mass in air ( lb) can be determined by using the formula:

$m = \dfrac{P_1V_1}{RT}$

where;

R = 53.3533 ft.lbf/lb.R°

$m = \dfrac{2088 \ lb/ft^2 \times 0.02518 \ ft^3}{53.3533 \ ft .lbf/lb.^0R \times 519 .67 ^0 R}$

m = 0.0018962 lb

From the tables of ideal gas properties at Temperature 519.67 R

$v_{r1} =158.58$

$u_1 = 88.62 Btu/lb$

At state of volume 2; the relative volume can be determined as:

$v_{r2} = v_{r1} \times \dfrac{V_2}{V_1}$

$v_{r2} = 158.58 \times 0.16$

$v_{r2} = 25.3728$

The specific energy $u_2$ at $v_{r2} = 25.3728$ is 184.7 Btu/lb

From the tables of ideal gas properties at maximum Temperature T = 5200 R

$v_{r3} = 0.1828$

$u_3 = 1098 \ Btu/lb$

To determine the relative volume at state 4; we have:

$v_{r4} = v_{r3} \times \dfrac{V_1}{V_2}$

$v_{r4} =0.1828 \times \dfrac{1}{0.16}$

$v_{r4} =1.1425$

The specific energy $u_4$ at $v_{r4} =1.1425$ is 591.84 Btu/lb

Now; the net work per cycle can now be calculated as by using the following formula:

$W_{net} = Heat \ supplied - Heat \ rejected$

$W_{net} = m(u_3-u_2)-m(u_4 - u_1)$

$W_{net} = m(u_3-u_2- u_4 + u_1)$

$W_{net} = m(1098-184.7- 591.84 + 88.62)$

$W_{net} = 0.0018962 \times (1098-184.7- 591.84 + 88.62)$

$W_{net} = 0.0018962 \times (410.08)$

$\mathbf{W_{net} = 0.777593696}$ Btu per cycle

the power developed by the engine, in horsepower. can be calculated as follows;

In the four-cylinder, four-stroke internal combustion engine; the power developed by the engine can be calculated by using the expression:

$W = 4 \times N' \times W_{net$

where ;

$N' = \dfrac{2400}{2}$

N' = 1200 cycles/min

N' = 1200 cycles/60 seconds

N' = 20 cycles/sec

W = 4 × 20 cycles/sec × 0.777593696

W = 62.20749568 Btu/s

W = 88.0144746 hp

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Answer:

Assumption:

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4. The process is stated to be reversible

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a. This is reversible adiabatic(i.e isentropic) process and thus $s_{1} =s_{2}$

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Answer:

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Explanation:

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We have;

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