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3 years ago

A sound wave traveling downward with a speed of about 4,000 m/s suddenly slows to 1,500 m/s not far below the Earth’s surface.

Physics

2 answers:

WINSTONCH [101]3 years ago

5 0

Speed of sound wave depends on the elasticity of medium

It is given by formula

$v = \sqrt{\frac{E}{\rho}}$

now if we are given that initially sound wave is travelling with speed 4000 m/s

Then its speed becomes 1500 m/s

so here since speed is decreased by large value

so here elasticity must decreased by large amount

A. a different kind of rock

B. an underground lake

C. an open cavity

D. a pile of dinosaur bones

So in above all options the density is changed or decreased by large value if the medium is changed to solid to liquid

So the correct answer will be

<em>B. an underground lake </em>

alexira [117]3 years ago

4 0

Answer: An underground lake

Hope that helped :D

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Explain a lever and a pivot in a full sentence

worty [1.4K]

Answer:

The lever is a movable bar that pivots on a fulcrum attached to a fixed point. The lever operates by applying forces at different distances from the fulcrum, or a pivot. As the lever rotates around the fulcrum, points farther from this pivot move faster than points closer to the pivot.

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2 years ago

Which of the following statements are true concerning the creation of magnetic fields? Check all that apply. Check all that appl

anzhelika [568]

Answer:

A permanent magnet creates a magnetic field at all points in the surrounding region.

An electric current in a conductor creates a magnetic field at all points in the surrounding region.

A moving electric charge creates a magnetic field at all points in the surrounding region.

Explanation:

Magnet field is a region around the magnet in which the magnetic force can be experienced. A magnet has two poles: North pole and South pole. A Magnetic field originates from north pole and ends at south pole.

Magnets are of two types: Permanent magnet and temporary magnet.

A moving charge produces magnetic field. A stationary charge can not produce a magnetic field.

The rate of flowing charge constitutes an electric current. If the cardboard is placed around the current carrying conductor and the iron fillings spread around the cardboard then the iron nails get stick to it. It means that a current carrying conductor creates a magnetic field around it.

Therefore, the true statements from the given statements are as follows;

A permanent magnet creates a magnetic field at all points in the surrounding region.

An electric current in a conductor creates a magnetic field at all points in the surrounding region.

A moving electric charge creates a magnetic field at all points in the surrounding region.

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3 years ago

Which of these BEST explains how Earth's surface features are formed by moving tectonic plates? *

alexdok [17]

Answer: The spinning of Earth's outer core causes the lithosphere to break into individual plates and collide with each other.

Earth's surface forms because of this reason:

The spinning of Earth's outer core causes the lithosphere to break into individual plates and collide with each other.

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3 years ago

Which of the following cars have the most kinetic energy

faltersainse [42]

<h2>Hey There!</h2><h2>_____________________________________</h2><h2>Answer:</h2>

$\huge\boxed{OptionA}$

mass = 4 kg

velocity = 5 m/s^2

<h3 /><h3>Orange truck:</h3>

Mass= 2kg

Velocity = 7m/s^2

mass = 6 kg

velocity = 4m/s^2

<h3 /><h3>Green Car:</h3>

Mass = 8 kg

Velocity = 3 m/s^2

<h2>_____________________________________</h2><h2>SOLUTION:</h2>

By the equation of kinetic energy,

K.E = $\frac{1}{2} mv^2$

Where,

K.E is kinetic energy

m is mass

v is velocity

<h2>_____________________________________</h2><h3>Kinetic energy of Blue car:</h3>

Directly substitute the variables in the equation,

K.E = $\frac{1}{2}x4x5^2$

Simplify the equation,

K.E = 50 J

<h2>_____________________________________</h2><h3>Kinetic Energy of Silver Car:</h3>

Directly substitude the variable in the equation,

K.E = $\frac{1}{2}x6x4^2$

Simplify the equation,

K.E = 48J

<h2>_____________________________________</h2><h3>Kinetic Energy of Green Car:</h3><h3 />

Substitute the variables in the equation,

K.E = $\frac{1}{2}x8x3^2$

Simplify the Equation,

K.E = 36J

<h2>_____________________________________</h2><h3>Kinetic Energy of Orange Truck:</h3><h3 />

Substitute the variable,

K.E = $\frac{1}{2}x 2x7^2$

Simplify the equation,

K.E = 49J

As you can see that the highest value of kinetic energy is of Blue SUV thus it will be out answer.

<h2>_____________________________________</h2><h2>Best Regards,</h2><h2>'Borz'</h2><h3 /><h3 /><h3 /><h3 /><h2 /><h2 />

6 0

2 years ago

1. For a reaction to occur, energy must be

amm1812

For a reaction to occur, energy must be absorbed to break chemical bonds

<u>Explanation:</u>

Reactions can be classified as chemical reaction, nuclear reaction, thermal reaction. So in these three reaction types, the nature of energy will only be varying.

But in order to execute a reaction, there should be breaking of existing bonds and then formation of new bonds. So for breaking of the bonds of reactants, energy should be absorbed from the surrounding.

Then the extra energy will be released after forming the products. Thus, the process of absorption of energy will lead to endothermic process and the process of releasing of energy will lead to exothermic reaction. So for a reaction to occur, energy must be absorbed to break the chemical bonds.

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2 years ago