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3 years ago

PLEASE HELP ASAP

Physics

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alina1380 [7]3 years ago

8 0

Answer:

We mentioned in the study section of Lecture 2 that hydrogen and oxygen combine in the ratio of 1 to 8, but that this is not enough information for leading to the conclusion that two hydrogen atoms combine with one of oxygen to form a water molecule. A key idea is attributed to Avagadro who said that equal volumes of gas (at the same temperature and pressure) contain equal numbers of constituent atoms or molecules. Experiments show that two liters of hydrogen gas will combine with one liter of oxygen gas to form two liters of water vapor. Each hydrogen molecule in hydrogen gas consists of two hydrogen atoms bonded together. Likewise, two oxygen atoms bind to make a oxygen molecule.

A "model" of a physical process is used to represent what one actually observes, even though this is an "ideal" model and not expected to be correct in all respects. However, it is a good enough model to explain many of the properties of gases with sufficient accuracy.

The motion of gas particles can be used to explain the pressure exerted and the temperature of a gas. The pressure on a surface is due to the force on that surface divided by its area. The force comes about from the multiple impacts of individual gas particles. Temperature, on the other hand, is DEFINED in terms of the average kinetic energy assocated with the motion of the gas particles. The greater the kinetic energy, the greater the temperature. See the apparatus shown in Figure 7.6 of the text which gives a simple way of measuring the distributions of speeds of atomic particles.

To visualize how gas particles colliding with a container create pressure, see Website II.

Gas particles move in all possible directions with differing speeds. The Kinetic Energy (KE) of a gas particle is equal to 1/2 its mass times its speeds squared. That is KE = 1/2 M x V2 , where M is the mass of the gas particle and V is its speed. The gas particles have a range of speeds, just like cars on a road, but it is the average of the speed squared times the mass, or the average kinetic energy which characterizes the temperature of a gas.

High temperature is associated with high kinetic energies and low temperatures are associated with low kinetic energies. However, keep in mind that the kinetic energy, and in this case the temperature, is proportional to the mass times the speed squared. So heavy particles moving more slowly will have the same kinetic energy as light particles moving more rapidly. Also, because the kinetic energy varies as the square of the speed, if two particles have the same mass, but one moves twice as fast as the other, it will have four times the kinetic energy (or temperature).

If temperature is associated with kinetic energy of a gas, one could ask at this point what controls the temperature of solids and liquids. It turns out that it is the kinetic energy of the constituent atoms and molecules that characterize the temperature of liquids and solids as well. We show in class a transparency picturing a solid with its atoms rigidly connected to each other. We will discuss more about liquids and solids in the next lecture, based on chapter 8. However, for now, let's keep in mind that the atoms or molecules in a solid, although bound to its neighbors in a rigid structure, can oscillate back and forth, and it is this motion that characterizes the temperature of a solid (or in a similar manner, of a liquid as well). As before, rapid oscillations mean high temperatures, and slower oscillations are lower temperatures.

4 - The Three Temperature Scales

There are three temperature scales. In the United States, we commonly use the Farenheit scale while in most other nations, the Celsius or Centigrade scale is used. Figure 7.10 shows these two scales side by side. Water boils at 212 degrees Farenheit or 100 degrees Centigrade. Water freezes at 32 degrees Farenheit or zero degrees Centigrade. However, the most important temperature scale for scientific calculations is the absolute temperature scale, or the Kelvin scale. Zero degrees Kelvin is the coldest possible temperature: it can be physically interpreted as the situation where the atoms or molecules have zero kinetic energy...so this is a very natural temperature scale. Zero degrees Kelvin is also -273 degrees Centigrade. Water freezes at +273 degrees Kelvin and zero degrees Centigrate. Hence, a difference of one degree is the same on the Centigrade and Kelvin scales, but the zero points are different.

R.S. Panvini

9/2/2002Explanation:

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PLEASE HELP ME!!!!!!!

melamori03 [73]

This it you can do it boy or girl 

6 0

3 years ago

At the moment t = 0, a 20.0 V battery is connected to a 5.00 mH coil and a 6.00 Ω resistor. (a) Immediately thereafter, how does

insens350 [35]

(a) On the coil: 20 V, on the resistor: 0 V

The sum of the potential difference across the coil and the potential difference across the resistor is equal to the voltage provided by the battery, V = 20 V:

$V = V_R + V_L$

The potential difference across the inductance is given by

$V_L(t) = V e^{-\frac{t}{\tau}}$ (1)

where

$\tau = \frac{L}{R}=\frac{0.005 H}{6.00 \Omega}=8.33\cdot 10^{-4} s$ is the time constant of the circuit

At time t=0,

$V_L(0) = V e^0 = V = 20 V$

So, all the potential difference is across the coil, therefore the potential difference across the resistor will be zero:

$V_R = V-V_L = 20 V-20 V=0$

(b) On the coil: 0 V, on the resistor: 20 V

Here we are analyzing the situation several seconds later, which means that we are analyzing the situation for

$t >> \tau$

Since $\tau$ is at the order of less than milliseconds.

Using eq.(1), we see that for $t >> \tau$ , the exponential becomes zero, and therefore the potential difference across the coil is zero:

$V_L = 0$

Therefore, the potential difference across the resistor will be

$V_R = V-V_L = 20 V- 0 = 20 V$

(c) Yes

The two voltages will be equal when:

$V_L = V_R$ (2)

Reminding also that the sum of the two voltages must be equal to the voltage of the battery:

$V=V_L +V_R$

And rewriting this equation,

$V_R = V-V_L$

Substituting into (2) we find

$V_L = V-V_L\\2V_L = V\\V_L=\frac{V}{2}=10 V$

So, the two voltages will be equal when they are both equal to 10 V.

(d) at $t=5.77\cdot 10^{-4}s$

We said that the two voltages will be equal when

$V_L=\frac{V}{2}$

Using eq.(1), and this last equation, this means

$V e^{-\frac{t}{\tau}} = \frac{V}{2}$

And solving the equation for t, we find the time t at which the two voltages are equal:

$e^{-\frac{t}{\tau}}=\frac{1}{2}\\-\frac{t}{\tau}=ln(1/2)\\t=-\tau ln(0.5)=-(8.33\cdot 10^{-4} s)ln(0.5)=5.77\cdot 10^{-4}s$

(e-a) -19.2 V on the coil, 19.2 V on the resistor

Here we have that the current in the circuit is

$I_0 = 3.20 A$

The problem says this current is stable: this means that we are in a situation in which $t>>\tau$ , so the coil has no longer influence on the circuit, which is operating as it is a normal circuit with only one resistor. Therefore, we can find the potential difference across the resistor using Ohm's law

$V=I_0 R = (3.20 A)(6.0 \Omega)=19.2 V$

Then the battery is removed from the circuit: this means that the coil will discharge through the resistor.

The voltage on the coil is given by

$V_L(t) = -V e^{-\frac{t}{\tau}}$ (1)

which means that it is maximum at the moment when the battery is disconnected, when t=0:

$V_L(0)=.V$

And V this time is the voltage across the resistor, 19.2 V (because the coil is now connected to the resistor, not to the battery). So, the voltage across the coil will be -19.2 V, and the voltage across the resistor will be the same in magnitude, 19.2 V (since the coil and the resistor are connected to the same points in the circuit): however, the signs of the potential difference will be opposite.

(e-b) 0 V on both

After several seconds,

$t>>\tau$

If we use this approximation into the formula

$V_L(t) = -V e^{-\frac{t}{\tau}}$ (1)

We find that

$V_L = 0$

And since now the resistor is directly connected to the coil, the voltage in the resistor will be the same as the coil, so 0 V. This means that the coil has completely discharged, and current is no longer flowing through the circuit.

7 0

3 years ago

What is the change in potential energy if the distance separating the electron and proton is increased to 1.0 nm?

Vlada [557]

Answer:

$Ep=-2.3*10^{-19}J$

Explanation:

The change in potential energy can be expressed as:

$Ep=K.\frac{q1.q2}{r}$

where K is a constant with a value of $9*10^{9}\frac{N.m^{2}}{C^{2}}$ , q1 and q2 are the charges of the proton and the electron and r is the distance between them.

The charge for the proton is $+1.6*10^{-19}C$ and the charge for the electron is $-1.6*10^{-19}C$ .

Converting r=1.0nm to m:

$1.0nm*\frac{1*10^{-9}m}{1.0nm}=1*10^{-9}m$

Replacing values:

$Ep=9*10^{9}\frac{N.m^{2}}{C^{2}}.\frac{(+1.6*10^{-19}C).(-1.6*10^{-19}C)}{1*10^{-9}m}$

$Ep=-2.3*10^{-19}J$

5 0

3 years ago

A train travels 67 kilometers in 1 hours, and then 81 kilometers in 5 hours. What is its average speed?

Naddika [18.5K]

Answer: 24.7 km/h

Explanation:

1) Average speed definition and formula

The average speed is the total distance run divided by the time elapsed:

S = distance / time

2) Distance 1 = 67 km

3) Distance 2 = 81 km

4) Total distance traveled = 67 km + 81 km = 148 km

5) time 1 = 1 hour

6) time 2 = 5 hours

7) total time = time 1 + time 2 = 1 h + 5 h = 6 h

8) Average speed:

S = 148 km / 6 h = 24.7 km/h

4 0

3 years ago

The is the time it takes for a wave to complete one cycle.

hichkok12 [17]

Answer:

Time Period

Explanation:

3 0

3 years ago

Read 2 more answers