Answer:
electrons exist in specified energy levels
Explanation:
In its gold-foil scattering with alpha particles, Rutherford proved that the plum-pudding model of the atom theorised by Thomson was wrong.
From his experiment, Rutherford inferred that the atom actually consists of a very small nucleus, where all the positive charge is concentrated, and the rest of the atom is basically empty, with the electrons (negatively charged) orbiting around the nucleus at very large distance.
However, Rutherford did not specify anything about the orbits of the electrons. Later, Bohr predicted that the electrons actually orbit the nucleus in specific orbits, each orbit corresponding to a specific energy level. Bohr's model found confirmation in the observation of the emission spectrum lines: when an electron in one of the higher energy level jumps down into an orbit with lower energy, the atom emits a photon which has an energy exactly equal to the difference in energy between the two orbits (and this energy of the photon corresponds to a precise wavelength).
Answer:
Average recoil force experienced by machine will be 200 N
Explanation:
We have give mass of each bullet m = 50 gram = 0.05 kg
There are 4 bullets
So mass of 4 bullets = 4×0.05 = 0.2 kg
Initial speed of the bullet u = 0 m/sec
And final speed of the bullet v = 1000 m/sec
So change in momentum 
Time is given per second so t = 1 sec
We know that force is equal to rate of change of momentum
So force will be equal to 
So average recoil force experienced by machine will be 200 N
Answer:
w = 2w₀ the angular velocity of man doubles
Explanation:
In this exercise, releasing the weights reduces the moment of inertia
I= I₀ / 2
Therefore, since the platform system plus man is isolated, the kinetic moment must be conserved
L₀ = L
I₀ w₀ = I w
I₀ w₀ = I₀ / 2 w
w = 2w₀
therefore the angular velocity of man doubles
Answer:
d. 5 ohms
Explanation:
For resistors in parallel, the equivalent resistance is found with:
1/Req = ∑(1/R)
1/R = 1/15 + 1/15 + 1/15
1/R = 3/15
R = 15/3
R = 5
Answer:
The correct option is D
Explanation:
This question is incomplete because of the absence of the setup which as been attached below. The setup shows/determines/tests the friction of wood (which is a block material), since Jerry wants to test the friction between different types of materials, he will have to replace the wooden block with another type of block material of choice so as to determine the friction of that also.
In order to have a comprehensive experiment, Jerry can use 4-5 different types of block material in the course of the experiment.
