The first model of the atom was developed by JJ Thomson in 1904, who thought that atoms were composed purely of negatively charged electrons. This model was known as the 'plum pudding' model.
This theory was then disproved by Ernest Rutherford and the gold foil experiment in 1911, where Rutherford shot alpha particles at gold foil, and noticed that some went through and some bounced back, implying the existence of a positive nucleus.
In 1913, Niels Bohr proposed a model of the atom where the electrons were contained within quantized shells that orbited the nucleus. This was because it was impossible for the cloud of negative electrons proposed by Rutherford to exist, as the negative electrons would be drawn to the positive nucleus, and the atom would collapse in on itself.
In 1926, the Austrian physicist Erwin Schrödinger created a quantum mechanical model of the atom by combining the equations for the behavior of waves with the de Broglie equation to generate a mathematical model for the distribution of electrons in an atom.
However the model used today is closest to the Bohr model of the atom, using the quantized shells to contain the electrons.
For more info:
http://chemistry.about.com/od/chemistryglossary/a/debroglieeqdef.htm
Answer:
C. Both technicians A and B
Explanation:
From the physical definition, power is defined as the rate of a body doing work. It is expressed as
P = w/t watts
Where
w - is the work done or the energy of the system in joules
t - time
The unit of power is represented in watts.
Whenever there is a rate of change of energy in the system, it accounts for the efficiency of the power of the system.
Hence, the statements of both technicians are correct.
The bowling ball would need less because it has more of a Gravitational pull to the ground than the tennis ball does. The letters represent force = mass and acceleration. I hope this helps ✨✨
Answer:
The options are not provided, so i will answer in a general way.
We know that:
The movement is along a straight horizontal surface, then we have one-dimensional motion.
The speed is 2m/s
We want a graph of position vs time.
Now, remember the relation:
Distance = Speed*Time
Then we can write the position as a function of time as:
P(t) = 2m/s*t + P0
Where t is our variable, that represents time in seconds, and P0 is the position at time t = 0seconds, we can assume that this is zero.
Then the equation is:
P(t) = 2m/s*t
And the graph is something like:
Answer:
Chemical and Biological weathering.
Explanation:
Processes that break down and weaken earth minerals are known as weathering. Over time, this can lead to erosion, in which huge sections of rock and stone are carried away, changing landscapes. Physical weathering alters the material structure of rocks, while chemical weathering alters their chemical structure.
