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3 years ago

A sound wave has a frequency of 645 Hz in air

Physics

1 answer:

rodikova [14]3 years ago

7 0

Answer:

$-14.2^{\circ}C$

Explanation:

First of all, we can find the speed of the sound wave, which is given by:

$v=f \lambda$

where

f = 645 Hz is the frequency

$\lambda=0.5 m$ is the wavelength

Substituting,

$v=(645 Hz)(0.5 m)=322.5 m/s$

Now we can find the temperature of the air by using the following relationship:

$v = 331 m/s + 0.6 T$

where T is the temperature in Celsius degrees. Since we know v = 322.5 m/s, we can re-arrange the formula to find the temperature:

$T=\frac{v-331 m/s}{0.6}=\frac{322.5 m/s-331 m/s}{0.6}=-14.2^{\circ}C$

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Olenka [21]

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Kinetic energy is the energy from movement so whenever its moving the most / longest is your answer

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3 years ago

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A solution of phosphoric acid was made by dissolving 10.0 g H3PO4 in 100.0 mL water. The resulting volume was 104 mL. Calculate

OLEGan [10]

Answer:

density is 1.057 g/mL

mole fraction is 0.0180

molarity is 0.98 mol/L

mole fraction is 0.0180

Explanation:

Given data

acid mass = 10 g

water volume = 100 mL

total volume = 104 mL

density = 1 g/cm³

to find out

the density, mole fraction, molarity, and molality

solution

first we calculate the density that is = total mass g / volume of solution mL

total mass = mass of H3PO4 + water mass

so water mass = density x volume

water mass = 100 ml x 1.0 g/cm3

water mass = 100 g

so total mass = 110.00 g

so that

density = total mass g / volume of solution mL

density = 110 / 104 = 1.057 g/mL

now we calculate no of moles in solvent i.e = mass H2O / mlar mass H2O

no of moles in solvent = 100/18.015 = 5.55 moles

and no of moles in solute i.e = mass of H3PO4 / mlar mass in H3PO4

moles in solute i.e = 10/ 97.994 = 0.102 moles

so total moles is 5.55 + 0.102 = 5.652 moes

so now mole fraction = no of moles in solute / total moes

mole fraction = 5.55 / 5.65

mole fraction is 0.0180

now we calculate first

mole fraction in solute and solvent that is

mole fraction in solute = no of moles in solute/ total moles

mole fraction in solute = 0.102 /5.65

mole fraction in solute is 0.0180

and mole fraction in solvent that = no of moles in solvent/ total moles

mole fraction in solvent that = 5.55/ 5.65

mole fraction in solvent that is 0.982

so molarity = no of moles of solute / volume

molarity = 0.102/0.104

molarity is 0.98 mol/L

and molality is = no of moles of solute / mass

molality = 0.102 / 100

molality is 1.02 mol/kg

6 0

3 years ago

a freight train travels at v=60(1-e^-t) ft/s, where t is the elapsed time in seconds. Determine the distance traeled in tree sec

lesantik [10]

Answer

given,

$v = 60(1-e^{-t})\ ft/s$

t = 3 s

we know,

$v = \dfrac{dx}{dt}$

$a = \dfrac{dv}{dt}$

position of the particle

$dx = v dt$

integrating both side

$\int dx =\int 60(1-e^{-t}) dt$

$x = 60 t + 60 e^{-t}$

Position of the particle at t= 3 s

$x = 60\times 3+ 60 e^{-3}$

x = 182.98 ft

Distance traveled by the particle in 3 s is equal to 182.98 ft

now, particle’s acceleration

$a = \dfrac{dv}{dt}$

$a = \dfrac{d}{dt}60(1-e^{-t})$

$a = 60 e^{-t}$

at t= 3 s

$a = 60 e^{-3}$

a = 2.98 ft/s²

acceleration of the particle is equal to 2.98 ft/s²

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4 years ago

The freezer compartment in a conventional refrigerator can be modeled as a rectangular cavity 0.3 m high and 0.25 m wide with a

Anon25 [30]

Answer:

Thickness of Styrofoam insulation is 0.02741 m.

Explanation:

Given that,

Height = 0.25 m

Depth = 0.5 m

Power = 400 W

Temperature = 33°C

We need to calculate the area of Styrofoam

Using formula of area

$A=2(lb+bh+hl)$

Put the value into the formula

$A=2(0.3\times0.5+0.25\times0.5+0.5\times0.3)$

$A=0.85\ m^2$

Inner surface temperature of freezer

$T_{i}=-10°C=263\ K$

Outer surface temperature of freezer

$T_{o}=33+273=306\ K$

We need to calculate the thickness of Styrofoam insulation

Using Fourier law,

$q=\dfrac{kA}{L}(T_{o}-T_{i})$

$L=\dfrac{kA}{q}(T_{o}-T_{i})$

Put the value into the formula

$L=\dfrac{0.30\times0.85}{400}(306-263)$

$L=0.02741\ m$

Hence, Thickness of Styrofoam insulation is 0.02741 m.

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3 years ago

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Kaylis [27]

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