PHYSICS HIGH SCHOOL

Water _____.has a pH value of 0,
expands when it freezes
is less dense than ice,
dissolves in most substances

Answers

Answer 1
Answer: Water expands when it freezes (that's why you should never put closed, fully filled water bottles in the freezer !)
Answer 2
Answer:

Water expands when it freezes

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A man is standing on a weighing machine on a ship which is bobbing up and down with simple harmonic motion of period T=15.0s.Assuming the motion is vertical calculate the amplitude of the ship's motion, if the scale reading of the machine varies between limits of 55.0kg and 65.0kg.

Answers


Well, first of all, one who is sufficiently educated to deal with solving
this exercise is also sufficiently well informed to know that a weighing
machine, or "scale", should not be calibrated in units of "kg" ... a unit
of mass, not force.  We know that the man's mass doesn't change,
and the spectre of a readout in kg that is oscillating is totally bogus.

If the mass of the man standing on the weighing machine is 60kg, then
on level, dry land on Earth, or on the deck of a ship in calm seas on Earth,
the weighing machine will display his weight as  588 newtons  or as 
132.3 pounds.  That's also the reading as the deck of the ship executes
simple harmonic motion, at the points where the vertical acceleration is zero.

If the deck of the ship is bobbing vertically in simple harmonic motion with
amplitude of M and period of 15 sec, then its vertical position is 

                                     y(t) = y₀ + M sin(2π t/15) .

The vertical speed of the deck is     y'(t) = M (2π/15) cos(2π t/15)

and its vertical acceleration is          y''(t) = - (2πM/15) (2π/15) sin(2π t/15)

                                                                = - (4 π² M / 15²)  sin(2π t/15)

                                                                = - 0.1755 M sin(2π t/15) .

There's the important number ... the  0.1755 M.
That's the peak acceleration.
From here, the problem is a piece-o-cake.

The net vertical force on the intrepid sailor ... the guy standing on the
bathroom scale out on the deck of the ship that's "bobbing" on the
high seas ... is (the force of gravity) + (the force causing him to 'bob'
harmonically with peak acceleration of  0.1755 x amplitude).

At the instant of peak acceleration, the weighing machine thinks that
the load upon it is a mass of  65kg, when in reality it's only  60kg.
The weight of 60kg = 588 newtons.
The weight of 65kg = 637 newtons.
The scale has to push on him with an extra (637 - 588) = 49 newtons
in order to accelerate him faster than gravity.

Now I'm going to wave my hands in the air a bit:

Apparent weight = (apparent mass) x (real acceleration of gravity)

(Apparent mass) = (65/60) = 1.08333 x real mass.

Apparent 'gravity' = 1.08333 x real acceleration of gravity.

The increase ... the 0.08333 ... is the 'extra' acceleration that's due to
the bobbing of the deck.

                        0.08333 G  =  0.1755 M

The 'M' is what we need to find.

Divide each side by  0.1755 :          M = (0.08333 / 0.1755) G

'G' = 9.0 m/s²
                                       M = (0.08333 / 0.1755) (9.8) =  4.65 meters .

That result fills me with an overwhelming sense of no-confidence.
But I'm in my office, supposedly working, so I must leave it to others
to analyze my work and point out its many flaws.
In any case, my conscience is clear ... I do feel that I've put in a good
5-points-worth of work on this problem, even if the answer is wrong .

Which of the following absorbs the MOST heat energy?a. red objects
b. white objects
c. black objects
d. purple object

Answers

darker is warmer C. Black objects.
Black objects because light waves are attracted to darker objects.

A rock containing valuable minerals that can be mined is called A. An inorganic compound
B. An igneous rock
C. An ore
D. An organic compound

Answers

A rock containing valuable minerals that can be mined is called an ore. The correct option is C.

What is an ore?

Ore is a deposit of one or more valuable minerals present inside the Earth's crust.

Metals essential to industry and trade, such as copper, gold, and iron, are found in the most valuable ore deposits. Copper ore is mined for a number of industrialapplications.

Ore is natural rock or sediment that contains one or more valuable minerals, usually metals, and can be mined, treated, and sold for a profit.

Mining extracts ore from the Earth, which is then treated or refined, often through smelting, to extract valuable metals or minerals.

Crushing the rock is the first step in extractingore from it. Heap leaching, flotation, or smelting are methods for extracting ore from rock.

Thus, the correct option is C.

For more details regarding an ore, visit:

brainly.com/question/4712893

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What is the hinky pink for cloudy 24 hours?

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