Answer:
Hydrogen and helium compounds.
Explanation:
We know that the solar System was formed around <u>4.6 billion years ago, </u>due to the gravitational collapse of a giant interstellar molecular cloud.
This cloud is a type of interstellar cloud and its density and size permit the formation of molecules, most commonly molecular hydrogen.
Therefore the principal substances were found before planets began to form are hydrogen and helium compounds, besides Rocks, metals, most of them in gaseous form.
I hope it helps you!
Answer:

ΔK = 2.45 J
Explanation:
a) Using the law of the conservation of the linear momentum:

Where:


Now:

Where
is the mass of the car,
is the initial velocity of the car,
is the mass of train,
is the final velocity of the car and
is the final velocity of the train.
Replacing data:

Solving for
:

Changed to cm/s, we get:

b) The kinetic energy K is calculated as:
K = 
where M is the mass and V is the velocity.
So, the initial K is:



And the final K is:




Finally, the change in the total kinetic energy is:
ΔK = Kf - Ki = 22.06 - 19.61 = 2.45 J
Answer:
It's A
Explanation:
As the waves progress through the medium, the particles they are made of move perpendicular to the direction in which the waves move. The particles do not move with the wave. So waves transmit energy but not matter as they progress through a medium.
Density
is a value for mass, such as kg, divided by a value for volume, such as m3.
Density is a physical property of a substance that represents the mass of that
substance per unit volume. It is a property that can be used to describe a
substance.<span> </span><span>It has standard units of
kg/m^3 or g/mL.
So, the best answer is option C.</span>
Answer:

Explanation:
In this question we have given
mass of airplane=.6 Kg
Radius of horizontal circle,r=6m
Time taken to complete 1.6 revolution=5s
Therefore time taken to complete 1 revolution, t=
t=3.1 s
We have to find the speed of airplane
We will first find the distance covered by airplane in tracing one circle which is equal to circumference of circle
We know that
Circumference,d = 
or 

We know that speed=
............(1)
Put value of d and t in equation 1
speed=
