Answer:
Conservation of energy
Explanation:
The first law of thermodynamics is given by :
Here,
Q is amount of heat added to the system
is change in internal energy
W is amount of work done by the system
It is clear that the energy can be neither created nor destroyed, it remains conserved. Hence, first law of thermodynamics shows that conservation of energy.
Answer:
The atomic model in which electrons are treated as waves is called the wave mechanical model of the atom or the quantum mechanical model of the atom. Principal energy levels contains energy sublevels
Answer: Potassium(K)
Explanation:
its an alkali metal placed under sodium and its over rubidium, its also the first element of period 4
Answer:
C. At the instant the ball reaches its highest point.
Explanation:
When a body is thrown up, it tends to come down due to the influence of gravitational force acting on the body. The body will be momentarily at rest at its maximum point before falling. At this maximum point, the velocity of the body is zero and since force acting on a body is product of the mass and its acceleration, the force acting on the body at that point will be "zero"
Remember, F = ma = m(v/t)
Since v = 0 at maximum height
F = m(0/t)
F = 0N
This shows that the force acting on the body is zero at the maximum height.
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.
