Technician A says a 50/50 mix of antifreeze and

A 200 W vacuum cleaner is powered by an electric motor whose efficiency is 70%. (Note that the electric motor delivers 200 W of

Goshia [24]

Answer:

The rate at which this vacuum cleaner supply energy to the room when running is 285.71 Watts.

Explanation:

power efficiency of electric motor = 70% = 0.70

The power output of the vacuum cleaner = $P_o$ = 200 W

The power output of the vacuum cleaner = $P_i$

$Efficiency=\frac{P_o}{P_i}$

$0.70=\frac{200 W}{P_i}$

$P_i=\frac{200 W}{0.70}=285.71 W$

The rate at which this vacuum cleaner supply energy to the room when running is 285.71 Watts.

5 0

3 years ago

You are driving on a roadway with multiple lanes of travel in the same direction, and are approaching an emergency vehicle parke

solmaris [256]

Answer: a. Leave the lane closest to the emergency as soon as it is safe to do so, or slow down to a speed of 20 MPH below the posted speed limit.

Explanation:

Giving a way to the law enforcement vehicle and a medical emergency vehicle is necessary. If one approaches an emergency vehicle parked along the roadway one should change the lane as the vehicle may not move and the driver may also waste his or her time also one should also slow down his or her speed while approaching the vehicle as most of the emergency vehicle are in rush to reach the hospital so the driver should maintain some distance with the medical emergency vehicle.

7 0

3 years ago

Consider an aircraft powered by a turbojet engine that has a pressure ratio of 9. The aircraft is stationary on the ground, held

77julia77 [94]

Answer:

The break force that must be applied to hold the plane stationary is 12597.4 N

Explanation:

p₁ = p₂, T₁ = T₂

$\dfrac{T_{2}}{T_{1}} = \left (\dfrac{P_{2}}{P_{1}} \right )^{\frac{K-1}{k} }$

${T_{2}}{} = T_{1} \times \left (\dfrac{P_{2}}{P_{1}} \right )^{\frac{K-1}{k} } = 280.15 \times \left (9 \right )^{\frac{1.333-1}{1.333} } = 485.03\ K$

The heat supplied = $\dot {m}_f$ × Heating value of jet fuel

The heat supplied = 0.5 kg/s × 42,700 kJ/kg = 21,350 kJ/s

The heat supplied = $\dot m$ · $c_p(T_3 - T_2)$

$\dot m$ = 20 kg/s

The heat supplied = 20* $c_p(T_3 - T_2)$ = 21,350 kJ/s

$c_p$ = 1.15 kJ/kg

T₃ = 21,350/(1.15*20) + 485.03 = 1413.3 K

p₂ = p₁ × p₂/p₁ = 95×9 = 855 kPa

p₃ = p₂ = 855 kPa

T₃ - T₄ = T₂ - T₁ = 485.03 - 280.15 = 204.88 K

T₄ = 1413.3 - 204.88 = 1208.42 K

$\dfrac{T_5}{T_4} = \dfrac{2}{1.333 + 1}$

T₅ = 1208.42*(2/2.333) = 1035.94 K

$C_j = \sqrt{\gamma \times R \times T_5}$ = √(1.333*287.3*1035.94) = 629.87 m/s

The total thrust = $\dot m$ × $C_j$ = 20*629.87 = 12597.4 N

Therefore;

The break force that must be applied to hold the plane stationary = 12597.4 N.

5 0

3 years ago

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

tangare [24]

Answer:

e= 50 J/kg

Explanation:

Given that

Speed ,v= 10 m/s

Diameter of the turbine = 90 m

Density of the air ,ρ = 1.25 kg/m³

We know that mechanical energy given as

$E=\dfrac{1}{2}mv^2\ J$

That is why mechanical energy per unit mass will be

$e=\dfrac{1}{2}v^2\ J/kg$

Now by putting the values in the above equation we get

$e=\dfrac{1}{2}\times 10^2\ J/kg$

e= 50 J/kg

That why the mechanical energy unit mass will be 50 J/kg.

5 0

3 years ago

Thế nào là góc quay xe ?

slava [35]

Answer:

what's what is what is it return if you have any clue please let me know Translate in English and send me because most of them are are from English I think so

8 0

3 years ago