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3 years ago

Discuss how a sheet can be made water proof

Physics

1 answer:

Readme [11.4K]3 years ago

7 0

Answer:

made with the material that is water proof

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A piston-cylinder device contains Helium gas initially at 150 kPa, 20 o C, and 0.5m 3 . The helium is now compressed in a polytr

Molodets [167]

Answer:

Explanation:

Given

$P_1=150 kPa$

$T_1=20^{\circ}C$

$V_1=0.5 m^3$

$T_2=140^{\circ}C$

$P_2=400 kPa$

R for Helium $R=2.076$

$c_v=3.115 kJ/kg-K$

mass of gas $m=\frac{P_1V_1}{RT_1}$

$m=\frac{150\times 0.5}{2.076\times 293}$

$m=0.123 kg$

Similarly $V_2$ can be found

$\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}$

$V_2=0.264 m^3$

Work done $W=\int_{V_1}^{V_2}PdV$

$W=\frac{P_2V_2-P_1V_1}{n-1}$

$W=\frac{mR(T_2_T_1)}{n-1}$

Since it is a polytropic Process

therefore $PV^n=c$

$P_1V_1^n=P_2V_2^n$

$(\frac{V_1}{V_2})^n=\frac{P_2}{P_1}$

$(\frac{0.5}{0.264})^n=\frac{400}{150}$

$n=\frac{\ln 2.66}{\ln 1.893}$

$n=1.533$

$W=\frac{0.123\times 2.076(140-20)}{1.533-1}$

$W=57.48 kJ$

From Energy balance

$E_{in}-E_{out}=\Delta E_{system}$

Neglecting kinetic and Potential Energy change

$Q_{in}+W_{in}=change\ in\ Internal\ Energy$

Change in Internal Energy $\Delta U=u_2-u_1$

$\Delta U=mc_v(T_2-T_1)$

$\Delta U=0.123\times 3.115(140-20)$

$\Delta U=45.977 kJ$

$Q_{in}+57.48=45.977$

$Q_{in}=-11.50 kJ$

i.e. Heat is being removed

3 0

3 years ago

A key falls from a bridge that is 44 m above the water. It falls directly into a model boat, moving with constant velocity, that

Lady_Fox [76]

The time $t$ it takes for the key to fall 44 m is

$44\,\mathrm m=\dfrac12\left(9.8\,\dfrac{\mathrm m}{\mathrm s^2}\right)t^2\implies t=3.0\,\mathrm s$

(notice I'm taking the downward direction to be positive)

The boat, moving at a presumably constant speed, then has 3.0 s to travel 19 m to the point of impact, which means its speed must be

$v=\dfrac{19\,\mathrm m}{3.0\,\mathrm s}=6.3\,\dfrac{\mathrm m}{\mathrm s}$

6 0

3 years ago

An 1100-kg car traveling at 27.0 m/s starts to slow down and comes to a complete stop in 578 m. What is the magnitude of the ave

Trava [24]

Answer:

693.685 N

Explanation:

t = Time taken

u = Initial velocity = 27 m/s

v = Final velocity

s = Displacement = 578 m

a = Acceleration

m = Mass

Equation of motion

$v^2-u^2=2as\\\Rightarrow a=\frac{v^2-u^2}{2s}\\\Rightarrow a=\frac{0^2-27^2}{2\times 578}\\\Rightarrow a=-0.63062\ m/s^2$

Force

F = ma

$F=1100\times -0.63062\\\Rightarrow F=-693.6851\ N$

Magnitude of braking force required to stop the car is 693.685 N

7 0

3 years ago

The graph is the path Beth took on a walk.

PIT_PIT [208]

Answer:

Beth went back toward her origin

Explanation:

Please, see the attached image that represent's Beth's path.

She started her walk 2 meters from the origin (0) and after 6 seconds she headed back to position zero (0) the origin. Notice the second half of the graph as a segment going down, thus reducing her distance from the origin, and getting closer to it.

6 0

3 years ago

Read 2 more answers

If a car is traveling at 35 mph how far will the car travel in 2.5 hours

Vanyuwa [196]

Answer:

87.5 miles

Explanation:

d = s * t

d = 35 * 2.5

d =87.5

4 0

3 years ago

Discuss how a sheet can be made water proof​

Discuss how a sheet can be made water proof