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3 years ago

Why can't passenger planes fly very high?

1 answer:

4 0

It is not that jet engines perform better at higher altitude, but rather they are more fuel efficient. Performance is far greater at lower altitudes. Just think about when you are taking off and the airplane accelerates quickly and pitches way up. There's lots of extra thrust down low to allow that. The fuel/air ratio remains somewhat constant through the climb. As altitude increases, the air thin outs and therefore, so can the fuel flow. Airlines try for the most efficient routes and altitudes as possible to save money. They do however change altitudes in flight (higher or lower) when needed for weather and turbulence avoidance. --- And a note about the jet stream, it is relatively narrow and always curving, so the time an airliner would spend there is very short. And another thing, it flows mostly west to east isn't the U.S. so a westbound flight would be at a disadvantage. Airlines still fly high whether traveling East or West.

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If an object has a mass of 1417g and it is moved 47 meters in 90 seconds, how much power was used?

astraxan [27]

Mass of the object is given as

$m = 1417 g = 1.417 kg$

now the speed of object is given as

$v = \frac{d}{t}$

here we know that

$d = 47 m$

$t = 90 s$

now we will have

$v = \frac{47}{90} = 0.52 m/s$

now we will have kinetic energy of the object as

$KE = \frac{1}{2}mv^2$

$KE = \frac{1}{2}(1.417)(0.52)^2$

$KE = 0.19 J$

now the power is defined as rate of energy

so here we can find power as

$P = \frac{KE}{t}$

$P = \frac{0.19}{90} = 2.14\times 10^{-3} W$

so above is the power used for the object

3 0

3 years ago

At what speed should a ball of mass 2 kg be rolled in order to reach the other side of

Veronika [31]

Answer:

M g H = 1/2 M v^2 potential energy = kinetic energy

v^2 = 2 g H = 2 * 9.80 * 6 = 117.6 m/s^2

v = 10.8 m/s

(C)

6 0

1 year ago

Your bedroom gets direct sunlight through a window during the hottest part of the day. You ask your mom to turn down the thermom

ycow [4]

I want to say its cooled by reflection because of the foil, sun reflects off of the foil back into the atmosphere. I don't think it's conduction because I have the foil on my windows and it's never warm to the touch. it's not a liquid so I don't believe it's convection. The foil reflects the radiation so I don't think it's b, c or d. so I wanna say A but I'm not 100% sure

6 0

3 years ago

Describe how Ubuntu could help to lack of basic services challenges

Butoxors [25]

Explanation:

Ubuntu is somewhat a South African concept that involves charity, sympathy, and mainly underlines the concept of universal brotherhood. Hence this concept can help fight social challenges such as racism, crime, violence and many more. It can contribute to maintaining peace and harmony in the country at large

4 0

2 years ago

Read 2 more answers

a bucket of water of mass 20kg is pulled at a constant velocity up to a platform 40 meters above the ground. this takes 10 minut

erma4kov [3.2K]

Taking into account the information above, we know the average mass of the bucket of water may be m=20-5/2=17.5kg. As the bucket of water is pulled at a "constant velocity" the work required to raise the bucket to the platform transformed into the potential energy of the bucket of water. That is why it should be W=mgh=17.5*9.8*40=6860J

5 0

3 years ago