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2 years ago

15

Water is made of two hydrogen atoms and one oxygen atom bonded together. Julia is describing how water undergoes a physical chan

ge when it boils. She says that the particles shift to be farther apart and that the oxygen and hydrogen separate. She also says that the total mass of the steam is the same as the initial water, and that heat energy was required to cause the change. She finishes her description by saying that the steam can be turned back into water if it is cooled

2 answers:

Anastaziya [24]2 years ago

8 0

Explanation:

Steam evaporates as a gas into the air. even when you capture steam as it rises into the atmosphere, it can be turned back into h2o when cooled. because of evaporation, you will not get the same volume of water you started with.

Oksi-84 [34.3K]2 years ago

7 0

Answer:

C is correct answer trust me not B or A

Explanation:

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A slide whistle is an open-closed tube with an adjustable plunger that changes the length. You are playing the slide whistle and

Serjik [45]

Answer:

df / ft = -n 12 n= 1, 3, 5, ...

Explanation:

The speed of sound is

v = λ f

In a whistle that we approach by an open tube at one end and closed at the other, standing waves occur, which has a node in the closed part and a maximum in the open pate, whereby wavelength and the distance of the tube are related, the fundamental wave is

λ₁ = 4L

The harmonics are

λ₃ = 4L / 3

λ₅ = 4L / 5

The general formula

λₙ = 4L / n

with n = 1, 3, 5,…

We substitute and clear in the first equation

f = v n / 4L n = 1, 3, 5,…

Let's use derivatives to find the frequency change

df / dt = v n /4 dL⁻¹ / dt

d / dt (1/L) = - 1 / L² dL / dt

Where dL / dt = 8 cm / s

We replace

df / dt = - n v / L2 dL / dt

Let's calculate

df / dt = - n 340/152 8

df / ft = -n 12 n= 1, 3, 5, ...

4 0

2 years ago

A person wants to lose weight by "pumping iron". The person lifts an 80 kg weight 1 meter. How many times must this weight be li

statuscvo [17]

Answer:

37357 sec

or 622 min

or 10.4 hrs

Explanation:

GIVEN DATA:

Lifting weight 80 kg

1 cal = 4184 J

from information given in question we have

one lb fat consist of 3500 calories = 3500 x 4184 J

= 14.644 x 10^6 J

Energy burns in 1 lift = m g h

= 80 x 9.8 x 1 = 784 J

lifts required $= \frac{(14.644 x 10^6)}{784}$

= 18679

from the question,

1 lift in 2 sec.

so, total time = 18679 x 2 = 37357 sec

or 622 min

or 10.4 hrs

3 0

2 years ago

If an irregularly shaped object (such as a wrench) is dropped from rest in a classroom and feels no air resistance, it will:

Maslowich

Answer:

D) accelerate but will not spin.

Explanation:

On the off chance that there is no air resistance the object will accelerate yet won't turn, this is on the grounds that without air resistance same force is applied on each bit of the object. Force on each segment is coordinated descending i.e parallel force. So there is no force to deliver spin movement in it.

It will accelerate because of gravity

7 0

2 years ago

A solid cylindrical bar conducts heat at a rate of 25 W from a hot to a cold reservoir under steady state conditions. If both th

expeople1 [14]

Answer:

Using the new cylinder the heat rate between the reservoirs would be 50 W

Explanation:

Conduction could be described by the Law of Fourierin the form: $Q=kA\frac{T_1-T_2}{L}$ where $Q$ is the rate of heat transferred by conduction, $k$ is the thermal conductivity of the material, $T_1$ and $T_2$ are the temperatures of each heat deposit, $A$ is the cross area to the flow of heat, and ${L}$ is the distance that the flow of heat has to go.
For the original cylinder the Fourier's law would be: $kA_1\frac{T_1-T_2}{L_1}=25W$ , and if $A_1=\frac{\pi D_{1}^{2}}{4}$ , then the expression would be: $k\frac{\pi D_1^{2}}{4} \frac{T_1-T_2}{L_1}=25W$ where $D_1$ is the diameter of the original cylinder, and ${L_1}$ is the length of the original cylinder.
For the new cylinder, in the same fashion that for the first, Fourier's Law would be: $Q_2=k\frac{\pi D_2^2}{4}\frac{T_1-T_2}{L_2}$ ,where $Q_2$ is the heat rate in the second case, $D_2$ and ${L_2$ are the new diameter and length.
But, $D_2=2D_1$ and $L_2=2L_1$ , substituting in the expression for $Q_2$ : $Q_2=k\frac{\pi (2D_1)^2}{4}\frac{T_1-T_2}{2L_1}$ .
Rearranging: $Q_2=\frac{2^2}{2}(k\frac{\pi D_1^2}{4}\frac{T_1-T_2}{L_1})$ .
In the last declaration of $Q_2$ , it could be noted that the expressión inside the parenthesis is actually $Q_1$ , then: $Q_2=\frac{2^2}{2}(25W)=50W$ .
<u>It should be noted, that the temperatures in the hot and cold reservoirs never change.</u>

7 0

2 years ago

A star orbiting a black hole in a clockwise direction at a radial distance of 1.0 × 106 km is acted upon by a counterclockwise f

snow_tiger [21]

Answer:

$2.5 \times 10^{11} N-m$ upwards

Explanation:

Torque is the vector cross product of the force and radial distance.

$\tau = rF sin \theta$

$\tau = (1.0\times 10^6 \times 10^3) m \times 250 N\times sin 90^o \\\Rightarrow \tau= 2.5 \times 10^{11} N-m$

The direction of the torque would be perpendicular to the direction of the force and radial distance. The direction of the force is counter-clockwise. The direction of the torque would be upwards.

4 0

2 years ago