This statement is true. Early earth was much cooler than it is today.
This is because the pollution as well as the population number was very small compared to nowadays population and pollution.
The pollution mainly is causing a decay in the ozone layer which protects the earth from uv rays. Thus, more of these rays enter the atmosphere and increase the temperature.
The increase in population along with the decrease in green areas leads to the increase in the percentage of carbon dioxide in the atmosphere, which again leads to an increase in the temperature.
Answer:
0.767m
Explanation:
We are given that the time interval between each droplet is equal.
We are also given that the fourth drop is just dripping from the shower when the first hits the floor.
If they fall at the same time interval and we know that the distance between the shower head and floor are the same, they must therefore fall at the same velocity.
The distance between each drop has to be the same given that they fall at equal time intervals.
Let this distance be x.
We can then partition the entire height of the system into three parts (as shown in the diagram).
Hence, we can say that:
x + x + x = 2.3m
3x = 2.3m
=> x = 2.3/3 = 0.767m
Therefore, at the time the first drop hits the floor, the third drop is only 0.767 m below the shower head.
F=-ks
F=-(390)(.45)
F=-175.5 N
Work=force x displacement
Work= 175.5(0.45)
Work= 78.98 J
Work = ∆E =78.98 J
Answer=79J (first option)
Complete question :
A 12 m x 15 m house is built on a 12-cm-thick concrete slab.
What is the heat-loss rate through the slab if the ground temperature is 5°C while the interior of the house is 25°C
Answer:
3kW
Explanation:
Given the following :
Dimension of house :
Length = 12m
Width = 15m
Thickness of concrete slab (t) = 12cm
t in metres :
100cm = 1m
12cm = (12/100)m
= 0.12m
Ground temperature (Tg) = 5°C
Interior temperature = (Th) = 25°C
Thermal conductivity of concrete (K) is approximately 1 Wm/k
Using the relation:
Q = KA * [ (Th - Tg) / d]
A = Length * width = (12 *15) = 180
Q = (1 * 180) * [(25°C - 5°C) / 0.12]
Q = 180 * (20/0.12)
Q = 180 * 16.6666
Q = 3,000W = 3kW
Linear expansivity is a type of thermal expansion. It is described by a fraction that represents the fractional increase in length of a thin beam of a material exposed to a temperature increase of one degree Celsius. ... Linear expansivity is used in many real world applications.