Answer:
Wc = 7.84 weight of crown
Ww = 7.84 - 6.86 = .98 weight of water displaced
Density = 7.84 / .98 = 8 crown is 8 X that of water
Since gold has a density of 19.3 that of water the crown is certainly not 100 percent (if any) gold
Answer: The correct answer would be C. Salt crystals are hard and brittle because they are made up of atoms that combine by ionic bonding.
Explanation: All the other ones are chemical changes because a new substance is formed.
Answer:
B) Electrons and protons
Explanation:
Each proton has a positive charge, and each electron has a negative charge. If the atom is electrically neutral, there must be the same number of electrons and protons.
A) and C) are wrong. Neutrons have no charge, so they can't counteract that of the protons or the electrons.
D) is wrong. The atomic number is the number of protons, and the mass number is the number of protons plus neutrons. The neutrons can't counteract the charge of the protons,
Answer:
Vi = 24.14 m/s
Explanation:
If we apply Law of Conservation of Energy or Work-Energy Principle here, we get: (neglecting friction)
Loss in K.E of the Rock = Gain in P.E of the Rock
(1/2)(m)(Vi² - Vf²) = mgh
Vi² - Vf² = 2gh
Vi² = Vf² + 2gh
Vi = √(Vf² + 2gh)
where,
Vi = Rock's Speed as it left the ground = ?
Vf = Final Speed = 17 m/s
g = 9.8 m/s²
h = height of rock = 15 m
Therefore,
Vi = √[(17 m/s)² + 2(9.8 m/s²)(15 m)]
Vi = √583 m²/s²
<u>Vi = 24.14 m/s</u>
