Why do some coastal cities experience a moderation of temperature from water?

A carpenter builds an exterior house wall with a layer of wood 3.0 cm thick on the outside and a layer of Styrofoam insulation 2

Leno4ka [110]

Answer:

A. T=15.54 °C

B. Q/A= 0.119 W/m2

Explanation:

To solve this problem we need to use the Fourier's law for thermal conduction:

$Q= kA\frac{dT}{dx}$

Here, the rate of flow per square meter must be the same through the complete wall. Therefore, we can use it to find the temperature at the plane where the wood meets the Styrofoam as follows:

$\frac{Q}{A} =\frac{T_1-T_0}{d_w}k_w=\frac{T_2-T_1}{d_s}k_s\\T_1(\frac{k_w}{d_w}+\frac{k_s}{d_s})=T_2\frac{k_s}{d_s}+T_0\frac{k_w}{d_w}\\T_1=\frac{T_2\frac{k_s}{d_s}+T_0\frac{k_w}{d_w}}{\frac{k_w}{d_w}+\frac{k_s}{d_s}}\\T_1= 15.54 \°C$

Then, to find the rate of heat flow per square meter, we have:

$\frac{Q}{A}=\frac{T_1-T_0}{d_w}k_w=0.119 \frac{W}{m^2}\\\frac{Q}{A}=\frac{T_2-T_1}{d_s}k_s= 0.119 \frac{W}{m^2}$

$T_0: Temperature \ in \ the \ house\\T_1: Temperature \ at \ the \ plane \ between \ wood \ and \ styrofoam\\T_2: Temperature \ outside\\k_w: k \ for \ wood\\d_w: wood \ thickness\\k_s: k \ for \ styrofoam\\d_s: styrofoam \ thickness$

7 0

3 years ago

What two quantities are always conserved in a nuclear reaction equation?

kupik [55]

Answer:B

Explanation:

Option A:

In the nuclear reactions,neutron can be split into proton an electron.

In this case,the number of protons are increasing,increasing the atomic number.

Hence,the atomic number is not conserved.

Option B:

In any reaction the sum of number of neutrons and number of protons remain constant before and after the reaction.

Option C:

The mass number may change for the atoms.For example $\alpha$ emission reduces the atomic number by $2.$

Option D:

In the nuclear reactions,neutron can be split into proton an electron.

So,they number of neutrons may change.

7 0

3 years ago

A weightlifter raises a 200-kg barbell with an acceleration of 3 m/s^2. How much force does the weightlifter use to raise the ba

lesya692 [45]

F = mass x acceleration

We have mass = 200kg

and acceleration = 3 m/s^2 so...

F = (200)(3)

F = 600 N

4 0

3 years ago

A car accelerates uniformly from 10 m/s to 20 m/s in 4.2 seconds. what is the magnitute of its acceleration

Dafna1 [17]

A=Vf-Vi/t
a=20m/s-10m/s/4.2s
a=2.4m/s^2

6 0

3 years ago

Read 2 more answers

Two passengers are on a moving sidewalk at the airport. Passenger A is

Oksanka [162]

Answer:

V = - 2[m/s]

Explanation:

This is a classic problem of relative velocities, in order to solve it we must understand each of the velocities, given in the initial data of the problem.

VA = velocity of passenger A, = 1.5[km/h], it is the same velocity of the sidewalk

VB = 2 + 1.5 = 3.5 [km/h], that is the velocity observed by a person outside from the sidewalk.

And from the perspective of passenger B the speed of passanger A is:

VA-VB = - 2 [m/s]

It means that the passenger B is seen how passenger A is getting close to him and then passed.

8 0

3 years ago