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4 years ago

Why machines have energy efficiency less than 100%

1 answer:

6 0

Because of the conservation of energy. You get out of a machine the energy that you put in in an ideal situation. (energy works like a piggy bank. If you put in $1.00 you will never get out more than that). Since machines have internal friction, losses due to heating, air resistance while rotating etc. some of the energy you put in is lost. It is lost in compensating for these inefficiencies. The efficiency is the ratio of output to input. Since output is less than input you have a number that is less than 1.

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The surface of the paper is phosphorescent. When light shines on it, some of the energy is absorbed and re-emitted slowly over t

Ad libitum [116K]

Answer:

Explanation:

Recall that the hierarchy of wavelength color from minimum wavelength to maximum wavelength is:

$V < I < B < G < Y < O < R;$ and

$E \ \alpha \ \dfrac{1}{\lambda}$

As a result, blue light has a higher energy level than green and red light.

As a result, the surface glows due to the blue LED. The green LED, on the other hand, would not allow the surface to glow as much as the red LED, which has a lower energy level when compared to the green light. As a result, the red LED would not allow the surface to glow as well.

8 0

3 years ago

A horizontal clothesline is tied between 2 poles, 12 meters apart. When a mass of 4 kilograms is tied to the middle of the cloth

Olegator [25]

Answer:

T=26.03 N

Explanation:

Given that

Distance between poles = 12 m

Mass of block m= 4 kg

Sag distance = 5 m

Lets take tension in the clothesline is T.

The component of tension in vertical direction will be T cosθ.

By force balancing

2 T cosθ = 40

here $tan\theta =\dfrac{5}{6}$

θ=39.80°

2 T cos39.8 = 40

T=26.03 N

6 0

3 years ago

The centripetal force of an object of mass m is given by F(r)=mv2r, where v is the speed of rotation and r is the distance from

mr Goodwill [35]

Answer:

$\frac{dF}{dr} = -4.82$

Explanation:

As we know that the centripetal force is given as

$F = \frac{mv^2}{r}$

now we will have to find the rate of change in force with respect to its radial distance

so we have

$\frac{dF}{dr} = - \frac{mv^2}{r^2}$

so we have

m = 1000 kg

v = 13.89 m/s

r = 200 m

now we have

$\frac{dF}{dr} = -\frac{1000(13.89^2)}{200^2}$

$\frac{dF}{dr} = -4.82$

3 0

3 years ago

All of the alkali metals, Group 1, have one valence electron. Which of these would represent the oxidation number of the alkali

melamori03 [73]

The elements found in the Group 1, or the Alkali Metal Group, have electronic configurations that end in $s^{1}$ .This means that they have 1 electron readily available to release in order to achieve a stable state.

When these atoms release the valence electron, they will achieve a stable state. For example, Lithium's stable state will be $Li^{+}$ and Sodium will be $Na^{+}$ .

The oxidation state will then be +1.

The answer is C.

8 0

3 years ago

Read 2 more answers

Why does the speed of sound waves change in different mediums?

andrezito [222]

The answer is solely based on the length of space between atoms. In gaseous mediums, atoms are generally quite far apart allowing waves to be undisrupted in the process. In solids and liquids, sound waves are trapped/diluted in the relatively close atom distances

8 0

3 years ago