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4 years ago

14

Which best explains why a wood- burning fireplace represents an open system?

2 answers:

Anna11 [10]4 years ago

6 0

D. Fire requires oxygen

11111nata11111 [884]4 years ago

4 0

D-Because a fire requires oxygen from the atmosphere to burn

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Absorbed energy is said to be quantized. This means:____________ a) Energy is absorbed only by valence electrons. b) Energy caus

wlad13 [49]

Answer:Energy is absorbed in exact amounts that correspond to differences in energy levels.

Explanation:

According to Bohr's theory, an electron moves from a lower to a higher energy level when it absorbed photon of a given energy. The energy of the photon absorbed must be equal to the energy difference between the higher and lower energy level. Thus energy is absorbed only in discreet amounts that correspond to differences in energy levels. Absorption of energy in discreet amounts is what is meant by the term 'quantization'.

4 0

3 years ago

In a laboratory, you determine that the density of a certain solid is 5.23×10−6kg/mm3. Convert this density into kilograms per c

kiruha [24]

Answer:

$5.23\cdot 10^3 kg/m^3$

Explanation:

The density of the solid is

$d = 5.23\cdot 10^{-6}kg/mm^3$

we want to convert it into kg/m^3. We must note that:

$1 m^3 = 1 m \cdot 1 m \cdot \1m =1000 mm\cdot 1000 mm \cdot 1000 mm=1\cdot 10^9 mm^3$

Therefore, the conversion can be done as follows:

$d=5.23\cdot 10^{-6} \frac{kg}{mm^3} \cdot (1\cdot 10^9 \frac{mm^3}{m^3}) =5.23\cdot 10^3 kg/m^3$

8 0

3 years ago

As computer information technology becomes faster, how does the ability of scientists to collect and organize data change?

irina1246 [14]

Because computers and technology develop and become faster things are going to<span> become substantially easier.</span>

7 0

4 years ago

cho hệ cơ học như hình vẽ hai đầu dây buộc hai vật có khối lượng tương ứng là m1=2kg và m2>m1 lấy g=10m/s sau 1s kể từ lúc bắ

Sever21 [200]

xin lỗi không có sơ đồ vui lòng cho biết sơ đồ

7 0

3 years ago

A mover uses a ramp to load a crate of nails onto a truck. The crate, which must be lifted 1.5 m from the street to the bed of t

jonny [76]

Answer:

<h2>3</h2>

Explanation:

Using the efficiency formula. Efficiency = MA/VR * 100%

MA = Mechanical Advantage

VR = velocity ratio = $\frac{distance\ moved\ by\ effort}{distance\ moved\ by\ load}$

Distance moved by effort = 4.5m

distance moved by load = 1.5m

VR = 4.5/1.5 =3

Assuming efficiency is 100% (since friction can be ignored)

100% = MA/3 * 100%

1 = MA/3

MA = 3*1

MA = 3

Mechanical Advantage of the ramp is 3

8 0

4 years ago