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:

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:

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


By using the equation speed = distance/time we can solve for distance. The speed is 4 m/s and the time is 12 seconds. We need to rearrange the equation to Speed * Time = distance. 4(12) = 48; 48 = distance. The cliff is 48 meters high.
Sue from Burkey and Keith from Baron will meet in 2 minutes
Answer: Option b
<u>Explanation:</u>
Time taken can be calculated when distance and the speeds are given. Here speeds of Keith and Sue are given. So, we have to find the relative speeds in order to calculate the time taken.
When two objects travel in same direction the relative speed will be the difference between speeds. Similarly when two objects travel in opposite direction, the relative speed will be the sum of given speeds.
Given:
Speed of Sue from Burkey is 6 km/hr and speed of Keith from Baron is 3 km/hr.
The distance between Burkey and Baron is 300 m.
From the formula, 
where d is distance,s is speed and t is time
It can be derived that, 
s = sum of given speeds = 3 km/hr + 6 km/hr = 9 km/hr
d = 300 m = 0.3 km

Answer:
Son aquellas ondas que no necesitan un medio material para propagarse. Incluyen, entre otras, la luz visible y las ondas de radio, televisión y telefonía. Todas se propagan en el vacío a una velocidad constante, muy alta (300 0000 km/s) pero no infinita.