A pinion and gear pair is used to transmit a power of 5000 W. The teeth numbers of pinion

Tems11 [23]

Answer:

Power of a machine is defined as its rate of doing work. It is the rate of transfer of energy. The power of a machine is said to be one watt if it can work at the rate of one joule in one second.

Explanation:

8 0

2 years ago

A stainless steel (AISI 304) tube used to transport a chilled pharmaceutical has an inner diameter of 36 mm and a wall thickness

Bingel [31]

Answer:

a) heat gain per unit tube length = $\frac{23-6}{1.35} = 12.6W/m$

b) heat gain per unit tube length = $\frac{23-6}{2.20} = 7.7W/m$

Explanation:

Assumptions:

Constant properties
Steady state conditions
Negligible effect of radiation
Negligible constant resistance between tube and insulation
one dimensional radial conduction

a) What is the heat gain per unit tube length

$R_{conv,i}'=\frac{1}{2\pi r_1h_i}$

$d_1=36mm$ Therefore $r_1=\frac{d_1}{2} =36/2=18mm=18*10^{-3}$

$r_2=2mm=2*10^{-3}m$

$k_{st}=14.2W/m.k$

$h_o=6W/m^2$

$h_i=400W/m^2$

$R_{conv,i}'=\frac{1}{2\pi * 1.8*10^{-3}*400}= 0.221m.K/W$

$R_{cond,st}'=\frac{ln(r_2/r_1)}{2\pi k_{st}} =\frac{ln(20/18)}{2\pi *14.2} =1.18*10^{-3}m.K/W$

$R_{conv,o}'=\frac{1}{2\pi r_2h_0}=\frac{1}{2\pi *2*10^{-3}*6}=1.33m.K/W$

$R_{tot}'=R_{conv,i}'+R_{cond,st}'+R_{conv,o}'=0.221+(1.18*10^{-3})+1.33=1.35m.K/W$

heat gain per unit tube length = $\frac{23-6}{1.35} = 12.6W/m$

b) What is the heat gain per unit length if a 10-mm-thick layer of calcium silicate insulation (k_ins = 0.050 W/m.K) is applied to the tube

$r_3=r_1+r_2+10mm=30mm=0.03m$

$R_{conv,i}'$ and $R_{cond,st}'$ are the same, but $R_{conv,o}'$ changes.

Therefore:

$R_{conv,o}'=\frac{1}{2\pi r_3h_0} = \frac{1}{2\pi *0.03*6}=0.88m.K/W$

$R_{conv,ins}'=\frac{ln(r_3/r_)}{2\pi k_{ins}} =\frac{ln(30/20)}{2\pi *0.05} =1.29m.K/W$

The total resistance $R_{tot}'=R_{conv,i}'+R_{cond,st}'+R_{conv,ins}'+R_{conv,o}'=0.221+(1.18*10^{-3})+1.29+0.88=2.20m.K/W$

heat gain per unit tube length = $\frac{23-6}{2.20} = 7.7W/m$

8 0

3 years ago

Read 2 more answers

When using fall arrest, free fall must be kept at or below how many feet

SashulF [63]

<h3>Answer:</h3>

two feet or less

<h3>Explanation:</h3>

8 0

3 years ago

A cylindrical bar of metal having a diameter of 20.3 mm and a length of 205 mm is deformed elastically in tension with a force o

Zarrin [17]

Answer:

a) 0.4393 mm

b) -0.141 mm

Explanation:

Cylindrical bar : Diameter = 20.3 mm , Length = 205 mm

Force that deforms bar of metal = 46400 N

elastic modulus = 66.9 GPa

Poisson's ratio ( u ) = 0.32

A) Determine the amount by which this specimen will elongate in the direction of applied stress

dl = $\frac{P*L}{A*E}$

where P = 46400 N

L = 205 mm

A = $\frac{\pi }{4} * 20.3^2$ = 323.65

E = 66.9 GPa

dl = ( 46400 * 205 ) / ( 323.65 * 66.9 * 10^3 ) = 0.4393 mm

B) determine the change in diameter of the specimen

change in diameter( compressed due to elongation in length )

= - u * dl

= - 0.32 * 0.4393

= -0.141 mm

5 0

3 years ago

Use the diagram to determine total resistance. (Round the FINAL answer to one decimal place.) Note: Use the rated voltage and wa

Valentin [98]

Answer:

22.6622 Ω ≈ 22.7 Ω
5.29516 A ≈ 5.3 A

Explanation:

For an electric motor, 1 hp = 746 W, so 1/2 hp = 373 W. Then the total wattage of the load is ...

Pl = 373 +100 +100 +75 = 648 W

The equivalent resistance is ...

R = V^2/P = (120 V)^2/(648 W) = 22 2/9 Ω

Adding the wiring resistance, we get a circuit resistance of ...

22.2222 +0.22 +0.22 = 22.6622 Ω . . . . total circuit resistance

Then the circuit current is ...

120 V/(22.6622 Ω) ≈ 5.29516 A

Circuit resistance is about 22.7 Ω; circuit current is about 5.3 A.

_____

Exact values are 5099/225 ohms and 27000/5099 amps. Of course, these assume the motor and lamps are purely resistive, which they are not.

3 0

3 years ago