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Lubov Fominskaja [6]
3 years ago
12

The emissivity of an ideal reflector has which of the following values?

Physics
1 answer:
Wittaler [7]3 years ago
4 0

Emissivityis a measure of how much thermal radiation a body emits to its environment. On the other hand we have that reflectivity is a measure of how much is reflected, and transmissivity  is a measure of how much passes through the object. If a body is required to be ideally reflective to its maximum efficiency, the body should NOT have the property of transmissivity or emissivity. Therefore it should be 0 its emittivity.

Correct answer would be A : ZERO.

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A car moving with an initial speed v collides with a second stationary car that is one-half as massive. After the collision the
Mashutka [201]

Answer:

4v/3

Explanation:

Assume elastic collision by the law of momentum conservation:

m_1v = m_1v_1 + m_2v_2

where v is the original speed of car 1, v1 is the final speed of car 1 and v2 is final speed of car 2. m1 and m2 are masses of car 1 and car 2, respectively

Substitute m_2 = m_1/2 \& v_1 = v/3

m_1v = \frac{m_1v}{3} + \frac{m_1v_2}{2}

Divide both side by m_1, then multiply by 6 we have

6v = 2v + 3v_2

3v_2 = 4v

v_2 = \frac{4v}{3}

So the final speed of the second car is 4/3 of the first car original speed

5 0
3 years ago
What are four types of pathogens and what type of disease or sickness do they cause?
Zanzabum

Bacteria( cholera)

Virus( AIDS)

Fungi(athlete's foot)

Protist( malaria)

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7 0
3 years ago
A garden hose has a radius of 0.0120 m, and water initially comes out at a speed of 2.88m/s. Dasha puts her thumb over the end ,
creativ13 [48]

Answer:

v = 12.4 [m/s]

Explanation:

With the speed and Area information, we can determine the volumetric flow.

V=v*A\\A=\pi *r^{2}

where:

r = radius = 0.0120 [m]

v = 2.88 [m/s]

A=\pi *(0.0120)^{2} \\A=4.523*10^{-4} [m]\\

Therefore the flow is:

V=2.88*4.523*10^{-4} \\V=1.302*10^{-3} [m^{3}/s ]

Despite the fact that you cover the inlet with the finger, the volumetric flow rate is the same.

v=V/A\\v=1.302*10^{-3} /1.05*10^{-4} \\v=12.4[m/s]

3 0
3 years ago
During a vaporization a substance changes from what to what
dusya [7]
A substance changes from liquid to gas
6 0
3 years ago
Read 2 more answers
A 200g(m2) mass is pulling the cart (m1) across the table as shown below. If it covers 1.12m in 4.8 seconds starting from rest,
Vsevolod [243]

Answer: 20.21 kg

Explanation:

The mass hanging from the pulley is pulling the cart. The force by which cart is being pulled is equal to weight of the hanging mass.

F=m_2g

⇒F=0.200 kg ×9.8 m/s²=1.96 N

Since there is no other force acting on the cart and there is no friction, so this force will pull the cart.

The Cart covers 1.12 m distance in 4.8 s.

From the equation of motion,

s = u t + 0.5 × a t²

We will find the acceleration of the cart,

Distance covered, s = 1.12 m

Initial velocity, u = 0 ( staring from rest)

Time taken, t = 4.8 s

⇒1.12 m = 0 + 0.5 × a × (4.8 s)²

⇒a = 0.097 m/s²

Now the force which causes this acceleration is:

F = ma

where m is the mass of the cart and a is the acceleration of the cart

⇒1.96 N = m×0.097 m/s²

⇒m = 20.21 kg

Hence, the mass of the cart is 20.21 kg.


4 0
3 years ago
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