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2 years ago

Which of the following is an example of a pulley?

Engineering

2 answers:

alexira [117]2 years ago

3 0

Answer:

Door knob

Explanation:

When the knob on one side of the door is turned, the shaft retracts the spring-loaded latch that holds the door closed. Without the knob in place, more force would be needed to turn the shaft and retract the latch.

kirill [66]2 years ago

3 0

That is the correct answer

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At a certain location, wind is blowing steadily at 10 m/s. Determine the mechanical energy of air per unit mass and the power ge

ale4655 [162]

Answer:

a) 50 J/kg

b) 721 67 KW

Explanation:

The velocity of the wind v = 10 m/s

diameter of the blades d = 70 m

efficiency of the turbine η = 30%

density of air ρ = 1.25 kg/m^3

The area of the blade A = $\pi d^2/4$

A = $\frac{3.142 * 70^2}{4}$ = 3848.95 m^2

The mechanical energy air per unit mass is gives as

e = $v^2/2$ = $\frac{10^2}{2}$ = 50 J/kg

Theoretical Power of the turbine P = ρAve

where

ρ is the density of air

A is the area of the blade

v is the velocity of the wind

e is the energy per unit mass

substituting values, we have

P = 1.25 x 3848.95 x 10 x 50 = 2405593.75 W

Actual power = ηP

where η is the efficiency of the turbine

P is the theoretical power of the turbine

Actual power = 0.3 x 2405593.75 = 721678.1 W

==> 721 67 KW

7 0

3 years ago

Lets Try This: study the pictures. Describe what you see and think about it. write your answer on a sheet of paper. home room

Yuliya22 [10]

Answer: I see three children cleaning the lawn while one of them are raking the leaves and one is holding a dust pan. The other child is holding a bucket. On the other picture, i see a young boy watering plants.

BTW: these pictures are not very clear so answers may vary.

Explanation:

4 0

2 years ago

A woodcutter wishes to cause the tree trunk to fall uphill, even though the trunk is leaning downhill. With the aid of the winch

Sedbober [7]

Answer:

The correct answer will be "400.4 N". The further explanation is given below.

Explanation:

The given values are:

Mass of truck,

m = 600 kg

g = 9.8 m/s²

On equating torques at the point O,

⇒ $T\times Cos(10+5)\times (1.3+4)=mg\times Sin(5)\times 4$

So that,

On putting the values, we get

⇒ $T\times Cos(15^{\circ})\times 5.3=600\times 9.8\times Sin(5^{\circ})\times 4$

⇒ $T=400.4 \ N$

8 0

3 years ago

Coal fire burning at 1100 k delivers heat energy to a reservoir at 500 k. Find maximum efficiency.

Marizza181 [45]

Answer:

55%

Explanation:

hot reservoir = 1100 K

cold reservoir = 500 K

This is a Carnot system

For a Carnot system, maximum efficicency of the system is given as

Eff = 1 - $\frac{Tc}{Th}$

where Tc = temperature of cold reservoir = 500K

Th = temperature of hot reservoir = 1100 K

Eff = 1 - $\frac{500}{1100}$

Eff = 1 - 0.45 = 0.55 or 55%

7 0

2 years ago

¿Cómo nos podría ayudar una hoja de cálculo en nuestro estudio?

Ghella [55]

Las hojas de cálculo en Excel facilitan los cálculos numéricos a través del uso de fórmulas; de manera fácil y rápida se pueden hacer operaciones aritméticas sobre cientos de miles de datos numéricos; por lo que se puede actualizar o corregir cualquiera de los datos numéricos y las operaciones se recalculan

3 0

2 years ago