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2 years ago

Which statement best describes balancing equations and the law of conservation of mass?

Physics

1 answer:

Dmitrij [34]2 years ago

5 0

Answer:

The number of atoms is the same in the reactants and in the products, and the total mass is the same in the reactants and in the products.

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A person sitting in a parked car hears an approaching ambulance siren at a frequency f1. as it passes him and moves away, he hea

natali 33 [55]

Answer:E

Explanation:

This can be explained by Doppler effect which gives the relation between apparent Frequency and actual frequency when the source of sound is moving

$f'=f\frac{v+v_o}{v-v_s}$

where $f'=apparent\ frequency$

$f=actual\ frequency$

$v=velocity\ of\ sound$

$v_o=velocity\ of\ observer$

$v_s=velocity\ of\ source$

here $v_o =0$ as observer is standing

when Ambulance is approaching then velocity of sound and velocity of ambulance have relative velocity thus denominator is less than and apparent frequency is more while when ambulance is going away then velocity of sound waves and velocity of observer is in opposite direction thus denominator is less than 1 and apparent frequency is less.

Thus $f_2$

6 0

4 years ago

a plane is flying 120 m above the ground at an angle of 30 degrees to the horizontal, when the pilot released 2 fuel tanks to de

charle [14.2K]

Answer:

2.26 seconds

97m/s

Explanation:

1. Fall time

i) Find the vertical speed of the plane when the tanks were released

$V_{y,0}=84m/s\times sin(30\º)=42m/s$

That is the same initial vertical speed of the tanks.

ii) Find the fall time

$y-y_0=V_{y,0}\cdot t+g\cdot t^2/2$

$120=42t+4.9t^2$

$4.9t^2+42t-120=0$

$t=\dfrac{-42\pm\sqrt{(42)^2-4(4.9)(-120)}}{2\times 4.9}$

Only the positive value has aphysical meaning: t = 2.26 seconds.

2. Speed when they hit the ground

i) The horizontal speed is constant:

$V_x=84m/s\times cos(30\º)\approx72.5m/s$

ii) The vertical speed is:

$V_y=V_{y,0}+g\cdot t$

$V_y=42m/s+9.8m/s^2\cdot (2.26s)\approx64.1m/s$

iii) Total speed

$V=\sqrt{V_x^2+V_y^2}$

$V=\sqrt{(72.5m/s)^2+(64.1m/s)^2}\approx97m/s$

6 0

4 years ago

Cuatro contenedores idénticos tienen la misma cantidad de gas helio a la misma temperatura inicial. Los recipientes también cuen

nikklg [1K]

Answer:

1) ΔE = -800 J, 2) ΔE = 200 J, 3) ΔE = -200 J, 4) ΔE = 800 J

Explanation:

For this exercise let's use the first law of thermodynamics

ΔE = Q + W

Where we will apply this expression to several cases

1) output Q = 500 J and does work of W = 300 J.

The two processes involve an energy output

ΔE = - 500 - 300

ΔE = -800 J

Therefore, the internal energy of the gas decreases by this amount,

2) enter Q = 500J and do work of W = 300 J

Positive heat is added and does negative work

ΔE = 500 - 300

ΔE = 200 J

3) they leave Q = 500 J and do (work on the gas) W = 300J

negative heat and positive work come out

ΔE = -500 + 300

ΔE = -200 J

4) heat enters Q = 500 J, work on gas W = 300 J

both positive

ΔE = 500 + 300

ΔE = 800 J

7 0

3 years ago

Two cars are sitting still. Car A has a mass of 2000 kilograms. Car B has a mass of 4000 kg. If the goal is to push both cars to

astra-53 [7]

Since car B has twice as much mass as car A has, it would require 2x as much force that it would need to push car A down.

If that was kinda confusing lemme say it again,

It would take twice as much that would be needed to push car B down than car A

Since everything is the same, basically two people would need to push down car B and one person for car A

Hope this helps

7 0

3 years ago

How is luminosity affected by other characteristics of a star

Nitella [24]

Answer:As the size of a star increases, luminosity increases. If you think about it, a larger star has more surface area. That increased surface area allows more light and energy to be given off. Temperature also affects a star's luminosity.

6 0

3 years ago