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3 years ago

Which of the following statements are true?Check all that apply.

Physics

1 answer:

MaRussiya [10]3 years ago

4 0

Answer:

1.The Sun is located at one of the foci of the planets' elliptical orbits.

2.The path of the planets around the Sun is elliptical in shape.

Explanation:

As per Kepler's law of planet motion we know that all planets revolve around the sun in elliptical path in such a way that position of Sun must be at one of the focii of the path

So all planets are in elliptical path always

Position of sun is always at one of the focus

so correct answer will be

1.The Sun is located at one of the foci of the planets' elliptical orbits.

2.The path of the planets around the Sun is elliptical in shape.

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An air conditioner runs 15 minutes each hour on a hot summer day. It is on a 240 volt circuit and uses 21 amps. Rate is $.10/kWh

Helen [10]

Answer:

Approximately $\$ 3.02$ .

Explanation:

Note that the electric rate in this question is in the unit dollar-per- ${\rm kWh}$ , where $1\; {\rm kWh}$ is the energy to run an appliance of power $1\; {\rm kW}$ for an hour.

Number of minutes for which the air conditioner is running in that day: $15 \times 24 = 360\; \text{minute}$ . Apply unit conversion and ensure that this time is measured in hours (same as the unit of the electric rate.)

$\begin{aligned} \text{time} &= 360\; \text{minute} \times \frac{1\; \text{hour}}{60\; \text{minute}} = 6\; \text{hour} \end{aligned}$ .

The power of this air conditioner is:

$\begin{aligned} \text{power} &= \text{voltage} \times \text{current} \\ &= 240\; {\rm V} \times 21\; {\rm A} \\ &= 5040\; {\rm W} \\ &= 5.04\; {\rm kW} \end{aligned}$ .

Thus, the energy that this air conditioner would consume would be:

$\begin{aligned}\text{energy} &= \text{power} \times \text{time} \\ &= 5.04\; {\rm kW} \times 6\; \text{hour} \\ &= 30.24\; {\rm kWh} \end{aligned}$ .

At a rate of $0.1$ dollar-per- ${\rm kWh}$ , the cost of that much energy would be approximately $3.02$ dollars (rounded to the nearest cent.)

6 0

2 years ago

A reciprocating compressor is a device that compresses air by a back-and-forth straight-line motion, like a piston in a cylinder

QveST [7]

Answer:

$\Delta \theta = 47.57^{\circ} C$

Explanation:

given,

moles of air compressed, n = 1.70 mol

initial temperature, T₁ = 390 K

Power supply by the compressor, P = 7.5 kW

Heat removed = 1.3 kW

Angular frequency of the compressor, f = 110 rpm = 110/60 = 1.833 rps.

Time of compression = time of the hay revolution

= $\dfrac{1}{2}\ T$

= $\dfrac{1}{2}\times \dfrac{1}{f}$

= $\dfrac{1}{2}\times \dfrac{1}{1.833}$

=0.273 s

Using first law of thermodynamics

U = Q - W

now,

$\dfrac{\Delta U}{\Delta t} = \dfrac{\Delta Q}{\Delta t}- \dfrac{\Delta W}{\Delta t}$

Power supplied $\dfrac{\Delta W}{\Delta t}$ = 7.5 kW

heat removed $\dfrac{\Delta Q}{\Delta t}$ = 1.3 kW

now,

$\dfrac{\Delta U}{\Delta t} = 7.5 -1.3$

$\dfrac{\Delta U}{\Delta t} = 6.2 kW$

we know,

$\dfrac{\Delta U}{\Delta t}=\dfrac{nC_v\Delta \theta}{\Delta t}$

C_v for air = 5 cal/° mol

= 5 x 4.186 J/mol°C = 20.93 J/mol°C

now,

$\Delta \theta = \dfrac{\Delta U}{\Deta t}\times \dfrac{\Delta t}{n C_v}$

$\Delta \theta = 6.2\times 10^3 \times \dfrac{0.273}{1.7\times 20.93}$

$\Delta \theta = 47.57^{\circ} C$

the temperature change per compression stroke is equal to 47.57°C.

4 0

3 years ago

A loop circuit has a resistance of R1 and a current of 1.9 A. The current is reduced to 1.5 A when an additional 3.1 Ω resistor

Deffense [45]

Answer:

11.625 Ohm

Explanation:

Let V be the Voltage charge of the loop, as this is constant we know that before the resistor addition the current I is:

V/R1 = 1.9 or V = 1.9R1

After the resistor addition to series R = R1 + 3.1

I = V/R = V/(R1 + 3.1) = 1.5

We can substitute V = 1.9R1

1.9R1 = 1.5R1 + 1.5*3.1

0.4R1 = 4.65

R1 = 4.65/0.4 = 11.625 Ohm

4 0

4 years ago

How to feel in this chart

xeze [42]

You can find them in a chart but the atomic mass unit (amu) is defined as the proton mass. Proton = 1amu, neutron =1 amu, electron = 0.005amu
charge on P is +1, charge on N is 0, and charge on electron is -1

3 0

4 years ago

Find the magnitude of the resultant force and the angle it makes with the positive x-axis. (Let a = 200 N and b = 400 N. Round y

omeli [17]

Answer: R = 346.4N and angle 30° to the horizontal negative axis

Explanation:

To find the resultant force, we need to sum up the forces on the vertical and horizontal axis.

For the horizontal axis;

Rx = -b + acos60

Rx = -400N +200cos60

Rx = -400N +100N

Rx = -300N

For the vertical axis;

Ry = asin60 = 200sin60

Ry = 173.2N

The resultant force R can be given as;

R = √(Rx^2 +Ry^2)

R = √((-300)^2 + 173.2^2)

R = 346.4N

Angle z can be written as

Tanz = Ry/Rx

z = taninverse (Ry/Rx)

z = taninverse (173.2/300)

z = 30°

6 0

3 years ago