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3 years ago

Plss help

Physics

1 answer:

Genrish500 [490]3 years ago

3 0

Answer:

Explanation:

imagine urself on an elevator dont you feel lighter

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Air expands isentropically from 2.2 MPa and 77°C to 0.4 MPa. Calculate the ratio of the initial to the final speed of sound.

djyliett [7]

Answer:

The ratio of initial to final speed of sound is given as 1.28.

Explanation:

As per the thermodynamic relation of isentropic expansion

$\frac{T_2}{T_1}=(\frac{P_2}{P_1})^{\frac{k-1}{k}}$

Here

$P_1$ is the pressure at point 1 which is given as 2.2 MPa
$T_1$ is the temperature at point 1 which is given as 77 °C or 273+77=350K

$P_2$ is the pressure at point 1 which is given as 0.4 MPa
$T_2$ is the temperature at point 2 which is to be calculated
k is the ratio of specific heats given as 1.4

Substituting values in the equation

$\frac{T_2}{350}=(\frac{0.4}{2.2})^{\frac{1.4-1}{1.4}}\\\frac{T_2}{350}=(0.18)^{0.2857}\\T_2=(0.18)^{0.2857} \times 350 \\T_2=0.61266 \times 350\\T_2=214.43 K$

As speed of sound c is given as

$c=\sqrt{kRT}$

for initial to final values it is given as

$\frac{c_i}{c_f}=\frac{\sqrt{k_1R_1T_1}}{\sqrt{k_2R_2T_2}}$

As values of k and R is constant so the ratio is given as

$\frac{c_i}{c_f}=\sqrt{\frac{T_1}{T_2}}$

Substituting values give

$\frac{c_i}{c_f}=\sqrt{\frac{350}{214.43}}\\\frac{c_i}{c_f}=\sqrt{1.63}}\\\frac{c_i}{c_f}=1.277 \approx 1.28$

So the ratio of initial to final speed of sound is 1.28.

5 0

3 years ago

Suppose you are standing such that a 35-foot tree is directly between you and the sun. If you are 7 feet tall and the tree casts

Juli2301 [7.4K]

Answer:

60 ft

Explanation:

The tree man and their shadow system forms two similar right angle triangles.

the figure is in the attachment.

let ∠BAC= θ

Therefore, in triangle ABC

tanθ = BC/AC= 35/75= 7/15

now in ΔAEF also

tanθ = EF/AE = 7/75-x= 7/15

solving we get x=60 ft

Now AC and FA are the shadows of the tree and the man respectively.

now FA =75-x=75-60= 15 ft

Therefore, the man must stand at a distance of 60 ft from the tree can you stand and still be completely in the shadow of the tree

3 0

4 years ago

5. It took 500 newtons of force to push a car 40 meters. How<br> much work was done?

Hunter-Best [27]

Answer:

Explanation:

work done=force * displacement

=500 N * 40 m

=2000 joule

6 0

3 years ago

Calculate the de Broglie wavelength of an electron traveling at 2.0 x 10^8 m/s (me = 9.1*10^-31 kg).

timofeeve [1]

Answer:

$\lambda=3.64\times 10^{-12}\ m$

Explanation:

We have,

Speed of an electron is $2\times 10^8\ m/s$

It is required to find the De Broglie wavelength of electron. The formula for the De- Broglie wavelength is given by :

$\lambda=\dfrac{h}{mv}$

h is Planck's constant

m is mass of an electron

Plugging all the values we get :

$\lambda=\dfrac{6.63\times 10^{-34}}{9.1\times 10^{-31}\times 2\times 10^{8}}\\\\\lambda=3.64\times 10^{-12}\ m$

So, the De-Broglie wavelength of an electron is $3.64\times 10^{-12}\ m$

4 0

3 years ago

The _______of force will determine the _______of acceleration.

loris [4]

ANSWER: the POWER of force will determine the SPEED of acceleration.

EXPLANATION

3 0

3 years ago