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Leona [35]
3 years ago
11

a penny dropped into a wishing well reaches the bottom in 1.5 seconds. what was the velocity at impact? i did -9.8 X 1.5 and got

-14.7... is it negative or positive? because the acceleration due to gravity is -9.8... idk help please asap
Physics
1 answer:
nexus9112 [7]3 years ago
3 0

Before you ever start doing a problem that involves direction, YOU DECIDE
which direction you're going to call positive.

If you call UP the positive direction, then the force of gravity is a negative
force (it pulls down), the acceleration of gravity is a negative acceleration
(because it's in the direction of a negative force), and things that are falling
have negative velocity.

It's your decision.

The acceleration due to gravity and the force of gravity are in the same
direction.  If something falls out of your hand, OF COURSE it's going to
move in the same direction as the force on it.

========================================

Let's say you decided to call UP the positive direction.
Then the acceleration of gravity, and the force of gravity, are both negative.

Now you throw a rock straight UP.

-- Its velocity is positive.

-- But its acceleration is negative, so its velocity is going to keep shrinking,
less and less, until it becomes zero.  (Top of the rock's trip.)

-- Since the negative acceleration points down, it eventually conquers
the upward velocity, and the velocity begins to point down (negative).

-- Now the acceleration is in the same direction as the velocity (both
are negative), so the velocity starts growing, becoming more and more
negative, as the acceleration keeps adding speed to it.

What does all this mean ?

When you throw a rock straight up, it goes slower and slower,
strops rising at some point, starts falling, then gets faster and
faster as it falls.

Everybody knows this as soon as they get to be 2 or 3 years old.
But they don't think about it in negative and positive velocity and
acceleration, until they get to high school and learn the language 
of Physics.

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Answer:

the energy when it reaches the ground is equal to the energy when the spring is compressed.

Explanation:

For this comparison let's use the conservation of energy theorem.

Starting point. Compressed spring

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Final point. When the box hits the ground

         Em_f = K = ½ m v²

since friction is zero, energy is conserved

          Em₀ = Em_f

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          v = \sqrt{ \frac{k}{m} }     x

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White light is an _____ mixture of all the colors.
Luba_88 [7]

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White light is a combination of all colors in the color spectrum.

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6 0
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Jon's bathtub is rectangular and its base is 18 ft2. (a) How fast is the water level rising if Jon is filling the tub at a rate
Kitty [74]

Answer:

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Answer:

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