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3 years ago

The percentage of incident light radiation reflected back to space is termed albedo. True or false?

Physics

1 answer:

liubo4ka [24]3 years ago

8 0

Answer:True

Explanation:

Albedo is a unit-less, non-dimensional quantity that shows how well a surface reflects solar energy. The value of albedo can vary from 0 to 1, 0 being the black and 1 refers to a white surface. Zero means Surface is a perfect absorber i.e. it absorbs all the incoming rays incidents on it. Albedo 1 means the surface is a perfect reflector.

Albedo usually applies for visible light, even though it may involve some of the infrared regions of the electromagnetic spectrum. The average albedo associated with earth surface is 30%

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In real machines,efficiency is always

Monica [59]

In real machines, efficiency is always less than 1 .

6 0

3 years ago

Read 2 more answers

Suppose your salary in 2012 is $70,000. Assuming an annual inflation rate of 7%, what salary do you need to earn in 2020 in orde

s2008m [1.1K]

Annual salary(2012) = $70,000

Annual inflation = 7%

Therefore, the salary you need to earn in 2020 in order to have the same purchasing power can be calculated below

$2020-2012=8\text{ years}$ $FV=PV\times(1+r)^n$

where

n = 8

r = 7/100 = 0.07

PV = 70, 000

$\begin{gathered} FV=70,000(1+0.07)^8 \\ FV=70000(1.07)^8 \\ FV\text{ = 70000}\times1.71818617983 \\ FV=120273.032588 \\ FV=\text{ \$}120,273.03 \end{gathered}$

The salary you need to earn in 2020 to have the same purchasing power = $120, 273.03

8 0

1 year ago

3. How long will it take a ball to reach the ground if it falls from a cliff 25 m tall (starting from rest)? What if the ball we

Nady [450]

Answer:

2.26 s

Explanation:

Let's take down to be positive.

Given (in the y direction):

Δy = 25 m

v₀ = 0 m/s

a = 9.8 m/s²

Find: t

Δy = v₀ t + ½ at²

25 m = (0 m/s) t + ½ (9.8 m/s²) t²

25 = 4.9t²

t = 2.26 s

If the ball instead had an initial horizontal velocity of 5 m/s, its initial vertical velocity is still 0 m/s. So the time to fall is still 2.26 s.

4 0

3 years ago

Prove that.. please help

GaryK [48]

$\large{ \boxed{ \bf{ \color{red}{Universal \: law \: of \: gravitation}}}}$

Every object in the universe attracts every other object with a force which is proportional to the product of their masses and inversely proportional to the square of the distance between them. The forces along the line joining the centre of the two objects.

❍ Let us consider two masses m1 and m2 line at a separation distance d. Let the force of attraction between the two objects be F.

According to universal law of gravitation,

$\large{ \longrightarrow{ \rm{F \propto m_1 m_2}}}$

Also,

$\large{ \longrightarrow{ \rm{ F \propto \dfrac{1}{ {d}^{2} } }}}$

Combining both, We will get

$\large{ \longrightarrow{ \rm{F \propto \dfrac{ m_1 m_2}{ {d}^{2}}}}}$

Or, We can write it as,

$\large{ \longrightarrow{ \rm{F \propto \: G \dfrac{ m_1 m_2}{ {d}^{2} }}}}$

Where, G is the constant of proportionality and it is called 'Universal Gravitational constant'.

☯️ Hence, derived !!

━━━━━━━━━━━━━━━━━━━━

8 0

3 years ago

The energy of an electromagnetic wave changes proportionally to which

ozzi

Answer:

D. Frequency

Explanation:

The energy of an electromagnetic wave is proportional to frequency, mathematically it is expressed as;

E ∝ f

E = hf

where;

h is Planck's constant = 6.626 x 10⁻³⁴ Js

The equation above can also be expanded to;

$E = hf = h \frac{c}{\lambda}$

where;

c is speed of light = 3 x 10⁸ m/s

λ is the wavelength of the electromagnetic wave

Since the speed of light is constant, we can conclude that the energy of the electromagnetic wave is directly proportional to its frequency and inversely proportional to its wavelength.

Therefore, the correct option for direct proportionality is FREQUENCY

8 0

3 years ago