Answer:
During convection, hot material expands & rises then moves to the side and cools & sinks. this circular pattern is called a convection current.
Explanation:
Convection is one of the three methods of transfer of heat. It occurs only in fluids (liquids or gases).
Convection occurs when there is a source of heat that heats a fluid, such as in a boiling pot of water. The water which is on the bottom of the pot becomes warmer before than the water at the top (because it is closer to the flame), and so it becomes less dense: for this reason, it expands and it becomes rising. On the contrary, the water on top is colder, so it is more dense and starts sinking, replacing the warmer water. As the new part of water gets warmer, it starts rising, and so the process is continuously repeated. This circular current is called convection current.
Answer:
$900 trillion
Explanation:
If Alaska is 20% of the contiguous US, then the approximate area of interest is ...
1200 miles × 3000 miles = 3.6×10^6 square miles.
The size of a dollar bill is about ...
(6.5 cm)·(15.5 cm) = 100.75 cm^2
One mile is 160,934.4 cm, so 1 square mile is about ...
1 mi^2 = (160,934.4 cm)^2 ≈ 2.59·10^10 cm^2
The number of dollars of interest is then ...
(3.6 · 10^6 mi^2)(2.59 · 10^10 cm^2)/(100.75 cm^2) ≈ 9.3·10^14
≈ 930 × 10^12 . . . dollars
It would cost about 900 trillion dollars to cover the land area of the US in $1 bills.
Answer:
t=1.623 sec
Explanation:
The distance traveled before the echo is had is:
Given the speed of sound as v=345m/s, we use the speed equation to solve for t:
Hence, it takes 1.623 seconds to hear the echo.
Answer:
I believe the answer is B.)
Answer:
the train is moving at the speed of v = 1.79 m/s
Explanation:
given,
rain drop is falling vertically down with the speed of = 3.84 m/s
angle of the rain drop = 25°
tan θ = 
tan 25° = 
v =3.84 × tan 25°
v = 1.79 m/s
hence, the train is moving at the speed of v = 1.79 m/s
