I am absolutely sure that if something is hot, it contain thermal energy only because <span>if a given body is heated its electrons start to move very fast which means that thermal energy is being produced. Hope everything is clear! Regards!</span>
Answer: 
Explanation:
The equation to calculate the center of mass
of a particle system is:

In this case we can arrange for one dimension, assuming the geometric center of the Earth and the ladder are on a line, and assuming original center of mass located at the Earth's geometric center:

Where:
is the mass of the Earth
is the mass of 1 billion people
is the radius of the Earth
is the distance between the center of the Earth and the position of the people (2 m above the Earth's surface)

This is the displacement of Earth's center of mass from the original center.
Answers:
a) 
b)
c) 
d) 
Explanation:
For this situation we will use the following equations:
(1)
(2)
Where:
is the <u>height of the model rocket at a given time</u>
is the i<u>nitial height </u>of the model rocket
is the<u> initial velocity</u> of the model rocket since it started from rest
is the <u>velocity of the rocket at a given height and time</u>
is the <u>time</u> it takes to the model rocket to reach a certain height
is the <u>constant acceleration</u> due gravity and the rocket's thrust
<h2>a) Time it takes for the rocket to reach the height=4.2 m</h2>
The average velocity of a body moving at a constant acceleration is:
(3)
For this rocket is:
(4)
Time is determined by:
(5)
(6)
Hence:
(7)
<h2>b) Magnitude of the rocket's acceleration</h2>
Using equation (1), with initial height and velocity equal to zero:
(8)
We will use
:
(9)
Finding
:
(10)
<h2>c) Height of the rocket 0.20 s after launch</h2>
Using again
but for
:
(11)
(12)
<h2>d) Speed of the rocket 0.20 s after launch</h2>
We will use equation (2) remembering the rocket startted from rest:
(13)
(14)
Finally:
(15)
Answer:
50 N
Explanation:
Since the refrigerator doesn’t move, that means the force of friction equals the amount of force the child exerts on the fridge. If the friction force were greater than the force by the child, the fridge would start accelerating towards the child. If it were less than the force the child exerted, the fridge would start accelerating away from the child. Therefore, the net force must be 0, in this case, the friction force is equal to the force the child exerted, for it to stay at rest (as Newton’s First Law stated).
I hope this helps! :)
Answer:
40 m/s.
Explanation:
From the question given above, the following data were obtained:
Initial velocity (u) = 60 m/s
Height (h) = 100 m
Acceleration due to gravity (g) = 10 m/s²
Final velocity (v) =?
The velocity at height 100 m can be obtained as follow:
v² = u² – 2gh (since the ball is going against gravity)
v² = 60² – (2 × 10 × 100)
v² = 3600 – 2000
v² = 1600
Take the square root of both side
v = √1600
v = 40 m/s
Thus, velocity at height 100 m is 40 m/s