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azamat
2 years ago
7

Bricks and insulation are used to construct the walls of a house. The

Physics
1 answer:
ira [324]2 years ago
7 0

Answer:

\dot Q=350.438\ W

Explanation:

Given:

<u>the thermal resistance in the form of </u>

R_1=\frac{x_1}{k_1} =0.095\ m^2.^{\circ}C.W^{-1}

R_2=\frac{x_2}{k_2} =0.704\ m^2.^{\circ}C.W^{-1}

where:

x_1\  \&\ x_2 are the thickness of the respective bricks

k_1\ \&\ k_2 are the respective coefficient of conductivity

temperature inside the house, T_h=24\ ^{\circ}C

temperature outside the house, \ T_c=10^{\circ}C

area of the wall, A=20\ m^2

Since the bricks and insulation are used to construct a wall then they must be used in series for better shielding.

<u>Using Fourier's law:</u>

\dot Q=k.A.\frac{dT}{x}

\dot Q={dT}\div {\frac{x}{k.A} }

in series the resistances get add up

\dot Q=dT\div (\frac{x_1}{k_1.A}+\frac{x_2}{k_2.A} )

\dot Q=(24-10)\div (\frac{0.095 }{20}+ \frac{0.704 }{20} )

\dot Q=350.438\ W

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A flat metal washer is heated. As the washer's temperature increases, what happens to the hole in the center? A flat metal washe
jenyasd209 [6]

answer;

The hole in the center of the washer will expand

explanation;

<em>A flat metal washer is heated. As the washer's temperature increases, what happens to the hole in the center? A flat metal washer is heated. As the washer's temperature increases, what happens to the hole in the center? The hole in the center will remain the same size. Changes in the hole cannot be determined without know the composition of the metal. The hole in the center of the washer will expand. The hole in the center of the washer will contract.</em>

this is an example of area expansivity.

coefficient of area expansivity is change in area per area per degree rise in temperature

a=dA/(A*dt)

as the temperature rises , there will be volumetric and area expansivity on the body. volume also increases because of the intermolecular forces of attraction between the molecule is now getting apart.

7 0
2 years ago
A particle decelerates uniformly from a speed of 30 cm/s to rest in a time interval of 5.0 s. It then has a uniform acceleration
wel

Answer:

V=20cm/s

Explanation:

The average speed is the distance total divided the time total:

V=X/T

First stage:

T1=5s

v_{f}  =v_{o} - at

But, v_{f}  =0   (decelerates to rest)

then: a =v_{o} /t=0.3/5=0.06m/s^{2}

on the other hand:

x =v_{o}*t - 1/2*at^{2}=0.3*5-1/2*0.06*5^{2}=0.75m

X1=75cm

Second stage:

T2=5s

x =v_{o}*t + 1/2*at^{2}=0+1/2*0.1*5^{2}=1.25m

X2=125cm

Finally:

X=X1+X2=200cm

T=T1+T2=10s

V=X/T=20cm/s

8 0
2 years ago
A solid element that is malleable' a good conductor of electricity, and reacts with oxygen is classified as a
Finger [1]
1) metal
Even though metalloids are also conductors of heat and electricity, malleable they are not as good as metals.
Metals are very good conductors of electricity and heat. They are also very hard to touch. Noble gases and non metals are the exact opposite in physical and chemical properties. Metals readily react with oxygen.
5 0
2 years ago
A child blows a leaf straight up in the air from rest. The leaf accelerates at 1.0\,\dfrac{\text m}{\text s^2}1.0 s 2 m1, point,
Neko [114]

Answer:

Time taken by the leaf to displace by 1.0 m distance is

t = \sqrt2 seconds

Explanation:

As we know that initial velocity of the leaf is given as

v_i = 0

now the acceleration upwards for the leaf is

a = 1 m/s^2

The displacement of leaf in upward direction is

d = 1 m

so now we have

d = v_i t + \frac{1}{2}at^2

1 = 0 + \frac{1}{2}(1) t^2

t = \sqrt2 seconds

3 0
2 years ago
Read 2 more answers
A tennis ball of mass m=0.060 kg and speed v=25 m/s strikes a wall at a 45 angle and rebounds with the same velocity at 45°. Wha
Diano4ka-milaya [45]

To solve this problem we will apply the concepts related to the Impulse which can be defined as the product between mass and the total change in velocity. That is to say

p = m\Delta v

Here,

m = mass

\Delta v = Change in velocity

As we can see there are two types of velocity at the moment the object makes the impact,

the first would be the initial velocity perpendicular to the wall and the final velocity perpendicular to the wall.

That is to say,

v_i = vcos\theta

v_f = -v sin\theta

El angulo dado es de 45° y la velocidad de 25, por tanto

v_i = (25)cos(45) = 17.68m/s

v_f = -(25)sin(45) = -17.68m/s

The change of sign indicates a change in the direction of the object.

Therefore the impulse would be as

p = 0.060(-17.68-17.68)

p = -2.12kg \cdot m/s

The negative sign indicates that the pulse is in the opposite direction of the initial velocity.

3 0
2 years ago
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