The illustration in figure below shows a uniform metre rule weighing 30 N pivoted on a wedge placed under the 40 cm mark and car
rying a weight of 70 N hanging 2 from the 10 cm mark. The ruler is balanced horizontally by a weight W hanging from the 100 cm mark. Calculate the value of the weight W.
1 answer:
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2. mass number
The mass number of an atom is equal to the sum of protons and neutrons inside its nucleus.
3. Atoms are made up of smaller particles.
According to Dalton's theory, atoms are the smallest particles that make matter, and they are indivisible and indestructible, so they are NOT made up of smaller particles.
4. a solid sphere
In Dalton's theory, atoms are not made of smaller particles, so we can think them as solid spheres.
5. J. J. Thomson
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6. An electron has the same amount of energy in all orbitals.
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7. A hydrogen atom in heavy water has an extra neutron.
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8. The glowing beam was always deflected by charged plates
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9. electrons move to a lower energy level
When electrons move from a higher energy level to a lower energy, they emit a photon (light) of energy equal to the difference in energy between the two energy levels.
10. orbital
In quantum mechanics, electrons in the atom are not precisely located, since we cannot determine their exact position and velocity at the same time. Therefore, we can only describe regions of space where the electrons have a certain probability to be found, and these regions of space are called orbitals.
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12. negative charge, found outside the nucleus
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13. move from higher to lower energy levels
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14. atomic number from its mass number
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- the atomic number of an atom (Z) is equal to the number of protons inside the nucleus
- the mass number of an atom (A) is equal to the sum of protons+neutrons inside the nucleus
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Number of neutrons = A - Z
15. None of them
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Answer:
d = 76.5 m
Explanation:
To find the distance at which the boats will be detected as two objects, we need to use the following equation:
<u>Where:</u>
θ: is the angle of resolution of a circular aperture
λ: is the wavelength
D: is the diameter of the antenna = 2.10 m
d: is the separation of the two boats = ?
L: is the distance of the two boats from the ship = 7.00 km = 7000 m
To find λ we can use the following equation:
<u>Where:</u>
c: is the speed of light = 3.00x10⁸ m/s
f: is the frequency = 16.0 GHz = 16.0x10⁹ Hz
Hence, the distance is:
Therefore, the boats could be at 76.5 m close together to be detected as two objects.
I hope it helps you!