7. When a wave crosses a surface at an angle from one medium into another, why does it change directions as it moves across the
1 answer:
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Answer:
Explanation:
= Avogadro's number =
e = Charge of electron =
k = Coulomb constant =
Z = Atomic number of water = 18
M = Molar mass of water = 0.018 kg/mol
m = Mass of person
The charge is given by
Total number of protons and electrons in each sphere
Electrical force is given by
The electrostatic force of attraction between them is
Answer:
- a) See explanation below
- b) At X.
Explanation:
Please, see the picture attached with the image of the plastic bottle for this question.
<u>(a) Explain why the water could not flow out of the bottle.</u>
What makes the water flow out of the botlle is the force of gravity, whic attracts the water towards the Earth.
When Johnson made a small hole at the bottom of the plastic bottle containing water, the air outside the bottle, which surrounds it and exerts a pressure all over the outer walls of the bottle, exerted a force against the small area of water "over" the hole that is in contact with the air.
Thus, this force of the air pushing upward through the wall opposed the force of gravity pulling downward making the net force zero and the water cannot fall.
<u>(b) To make the water flow out more easily, his teacher suggested making another hole. At which position - X, Y or Z, should he make the 2nd hole in order for the water to flow out the fastest?</u>
You must open the hole at a place where there is not water but air, such that the outer air can enter in the bottle.
That will make that the pressure in the space over the water inside the bottle be equal to the pressure outside.
The pressure of the air above the water will push it downward. Now, the force from the pressure of air inside the water, which is downward, opposes the upward force from the pressure of air around the first hole, and the net force will be downward, making the water flow out more easily.
Thus, the position where he should make the second hole in order for the water to flow fastest is at X.
Answer:
Fnet = 0
Explanation:
- Since the block slides across the floor at constant speed, this means that it's not accelerated.
- According Newton's 2nd Law, if the acceleration is zero, the net force on the sliding mass must be zero.
- This means that there must be a friction force opposing to the horizontal component of the applied force, equal in magnitude to it:
- In the vertical direction, the block is not accelerated either, so the sum of the normal force and the vertical component of the applied force, must be equal in magnitude to the force of gravity on the block:
⇒ 169 N + Fn = Fg = 216 N (3)
- This means that there must be a normal force equal to the difference between Fappy and Fg, as follows:
- Fn = 216 N - 169 N = 47 N (4)