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2 years ago

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

Physics

2 answers:

Anna11 [10]2 years ago

6 0

D. Fire requires oxygen

11111nata11111 [884]2 years ago

4 0

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

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HELP HELP HELP ME!!!

zzz [600]

I believe the answer is C. Hope this helps!!

7 0

2 years ago

Peter designed a road with a curve of radius 30 m that is banked so that a 950 kg car traveling at 40.0 km/h can round it even i

spayn [35]

Answer:

$v = 15.56 m/s$

$v = 56 km/h$

Explanation:

When coefficient of friction is approximately zero then we have

$F_ncos\theta = mg$

$F_n sin\theta = \frac{mv^2}{R}$

$tan\theta = \frac{v^2}{Rg}$

here we know that

$v = 40 km/h = 11.11 m/s$

R = 30 m

$tan\theta = \frac{11.11^2}{30\times 9.81}$

$\theta = 22.75 degree$

now when friction coefficient is 0.30 then we have

$F_n cos\theta = mg + F_f sin\theta$

$F_f cos\theta + F_n sin\theta = \frac{mv^2}{R}$

now we have

$v = \sqrt{Rg(\frac{\mu + tan\theta}{1 - \mu tan\theta})}$

$v = \sqrt{30(9.81)(\frac{0.30 + tan22.75}{1 - (0.30) tan22.75})}$

$v = 15.56 m/s$

$v = 56 km/h$

3 0

2 years ago

A student drops two metallic objects into a 120-g steel container holding 150 g of water at 25°C. One object is a 206-g cube of

spayn [35]

Answer:

Mass of the aluminium chunk = 278.51 g

Explanation:

For an isolated system as given the energy lost and gains in the system will be zero therefore sum of all transfer of energy will be zero,as the temperature will also remain same

A specific heat formula is given as

Energy Change = Mass of liquid x Specific Heat Capacity x Change in temperature

Q = m×c×ΔT

Heat gain by aluminium + heat lost by copper = 0 (1)

For Aluminium:

Q = $m\times0.897\frac{J}{g.k}\times(25-5)$

Q = m x 17.94 joule

For Copper:

$Q= 206g\times0.385\frac{J}{g.k} \times(88-25)$

Q= 4996.53 Joule

from eq 1

m x 17.94 = 4996.53

$mass of aluminium = \frac{4996.53}{17.94} g$

Mass of the aluminium chunk = 278.51 g

3 0

2 years ago

What are dimensionless quantities??

bearhunter [10]

Answer:

Characteristic numbers are dimensionless numbers used in fluid dynamics to describe a character of the flow. To compare a real situation with a small-scale model it is necessary to keep the important characteristic numbers the same. Names of these numbers were standardized in ISO 31, part 12.

Explanation:

7 0

2 years ago

Why is the answer A and not C?<br>please help!

MariettaO [177]

Answer:

because it gives a complete thought

4 0

1 year ago