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3 years ago

A long, circular aluminum rod is attached at one end to a heated wall and transfers heat by convection to a cold fluid.

Engineering

1 answer:

Trava [24]3 years ago

3 0

Answer:

a. Heat removal rate will increase

b. Heat removal rate will decrease

Explanation:

Given that

One end of rod is connected to the furnace and rod is long.So this rod can be treated as infinite long fin.

We know that heat transfer in fin given as follows

$Q_{fin}=\sqrt{hPKA}\ \Delta T$

We know that area

$A=\dfrac{\pi}{4}d^2$

Now when diameter will triples then :

$A_f=\dfrac{\pi}{4}{\left (3d \right )}^2$

$A_f=9A$

$Q'_{fin}=\sqrt{9hPKA}\ \Delta T$

$Q'_{fin}=3\sqrt{hPKA}\ \Delta T$

$Q'_{fin}=3Q$

So the new heat transfer will increase by 3 times.

Now when copper rod will replace by aluminium rod :

As we know that thermal conductivity(K) of Aluminium is low as compare to Copper .It means that heat transfer will decreases.

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"Water is flowing in a metal pipe. The pipe OD (outside diameter) is 61 cm. The pipe length is 120 m. The pipe wall thickness is

Katarina [22]

Answer:

Total wight =640.7927 KN

Explanation:

Given that

do= 61 cm

L =120

t= 0.9 cm

That is why inner diameter of the pipe

di= 61 - 2 x 0.9 cm

di=59.2 cm

Water density ,ρ = 1 kg/L = 1000 kg/m³

Weight of the pipe ,wt = 2500 N/m

wt = 2500 x 120 N = 300,000 N

The wight of the water

wt ' = ρ V g

$wt'=1000\times \dfrac{\pi}{4}\times (0.61^2-0.0592^2)\times 9.81\times 120 N$

wt'=340792.47 N

That is why total wight

Total wight = wt + wt'

Total wight =300,000+ 340792.47 N

Total wight =640,792.47 N

Total wight =640.7927 KN

7 0

4 years ago

A sign structure on the NJ Turnpike is to be designed to resist a wind force that produces a moment of 25 k-ft in one direction.

Jlenok [28]

Solution :

Finding the cohesion of the soil(c) using the relation:

$c = \frac{q_u}{2}$

Here, $q_u$ is the unconfined compression strength of the soil;

$c = \frac{800}{2}$

= 400 psf

∴ The cohesion value is greater than 0

So the use of the angle of internal friction is 0

Referring to the table relation between bearing capacity factors and angle of internal friction.

For the angle of inter friction $0^\circ$

$N_c = 5.14$

$N_q = 1.0$

$N_r = 0$

Therefore,

$q_{ult} = (400 \times 5.14 )+(110 \times 3 \times 1.0)+(0.5 \times 100 \times 13 \times 0)$

= 2386 psf

∴ Allowable bearing capacity $q_{a} = \frac{Q_{allow}}{A}$

$=\frac{30}{B^2}$

∴ $q_a = \frac{q_{ult}}{F.O.S}$

$\frac{30}{B^2} = \frac{2386}{3}$

∴ B = 0.2 ft

Therefore, the dimension of the square footing is 0.2 ft x 0.2 ft

$=0.04 \ ft^2$

7 0

3 years ago

Describe two factors that limit the design of roller coasters

serious [3.7K]

Answer:

The factors according to the given topic are summarized below.

Explanation:

The biggest aspect becomes G forces but instead if they are handled by that of the living organism.
Coasters were already continually changing, becoming special than it's ever been and year by year they hit unprecedented levels of tremendous growth. Higher, more quickly, prolonged although innovative components have been utilized.

3 0

3 years ago

Which dimensionless parameter tells whether flow disturbances will be attenuated or amplified? a. Pr b. Re C G d. St e. Fe

Aleonysh [2.5K]

Answer:

b. Re

Explanation:

Reynolds number describe the type of flow of fluid. If Reynolds number has a high value then it is called turbulent flow and if Reynolds number is low then it is called laminar flow. Reynolds number given as follows:

$Re=\dfrac{\rho VD}{\mu }$

For internal pipe flow, if Reynolds number greater than 4000 then, it is called turbulent flow and if Reynolds number less than 2000 then it is called laminar flow. The Reynolds number between 2000 to 4000 the flow is called transition flow.

7 0

4 years ago

Why is concrete on its own not a good material to use

Inga [223]

Answer:

It has poor tensile strength despite having high compressive strength

Explanation:

Concrete exhibits high compressive strength when used. However, it has very low compressive strength. This is the reason why concrete is normally combined with steel to make a composite building material called reinforced concrete. The steel reinforces concrete hence increasing the tensile strength in RC buildings. The end composite is durable and fireproof. Generally, the main reason why concrete is not use on its own is due to its poor tensile strength.

7 0

3 years ago