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3 years ago

What waves need molecules in order to transfer energy

Physics

1 answer:

nevsk [136]3 years ago

4 0

Answer:

Mechanical waves

Explanation:

Waves are periodic oscillations, that carry energy, but not matter.

Waves are classified into two types:

- Mechanical waves: these waves are produced by the oscillations of the particles in a medium, which can oscillate along the direction of propagation of the wave (longitudinal wave) or perpendicular to the direction of motion of the wave (transverse wave). These waves can only propagate in a medium, so they cannot travel in a vacuum. Examples of mechanical waves are sound waves.

- Electromagnetic waves: these waves are produced by the oscillations of electric and magnetic field. They are transverse waves. They are the only type of wave able to propagate through a vacuum (so, through space).

Therefore, the waves that need molecules in order to transfer energy are mechanical waves.

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What happens to a decimal place in the number when you are converting from a smaller metric unit to a larger unit?

Natasha_Volkova [10]

I dont have any idea :P

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3 years ago

A person walks 2 miles every day to work, leaving her front porch at 7:00 A.M. and arriving at work at 7:30 A.M. ON the way home

Nataly [62]

Answer:

The displacement is zero miles

Explanation:

The displacement of an object that moves from point A to point B is defined as

$d =B-A$

Where d is the displacement of the object. The displacement does not depend on the trajectory of the object. It only depends on the linear distance between the end point and the starting point.

In this case we know that the person walks from home to work and then walks from work to home. Therefore, the total displacement is the linear distance between the point where its journey begins and the point where the route ends.

The tour begins on the front porch of your house and ends on the front porch of your house (when you return from work). If we call A to the front porch of the house then the displacement is:

$d = A-A = 0$

The displacement is zero miles, since the person finishes the journey just where it started (front porch)

7 0

3 years ago

A hand moves a block vertically upward. Its speed slows down as it moves up (it is decelerating). The work done by gravity on th

Nataly_w [17]

Answer:

a. negative

b. zero

Explanation:

work is the change in the energy of a system due to external forces

work is done when a force moves a load through a distance in the direction of the force

The work done by a force on a system is positive when the force and the force displacement point in the same direction and negative when they point in opposite directions

in the scenario we are considering in the question, the force (the hand) moves the block vertically upwards but the displacement of the block reduces (in the opposite direction) since it decelerates. as such the work done by gravity on the block is negative.

the work done on the block is zero if the system consists of the block and the earth because there is no gravitational force exerted on the system

5 0

3 years ago

Hoover Dam on the Colorado River is the highest dam in the United States at 221m, with a power output of 680 MW. The dam generat

DiKsa [7]

Answer:

The power in this flow is $9.56\times10^{8}\ W$

Explanation:

Given that,

Distance = 221 m

Power output = 680 MW

Height =150 m

Average flow rate = 650 m³/s

Suppose we need to calculate the power in this flow in watt

We need to calculate the pressure

Using formula of pressure

$Pressure=\rho g h$

Where, $\rho$ = density

h = height

g = acceleration due to gravity

Put the value into the formula

$Pressure=1000\times9.8\times150$

$Pressure=1470000\ Nm^2$

We need to calculate the power

Using formula of power

$P=Pressure\times flow\ rate$

Put the value into the formula

$P=1470000\times650$

$P=9.56\times10^{8}\ W$

Hence, The power in this flow is $9.56\times10^{8}\ W$

5 0

3 years ago

There is a plate with moment of inertia Ip = 0.0711 kgm2 , rotating around its center of mass with angular speed of 4.53 rad/s.

Anna007 [38]

Answer:

1) their common angular speed = 3.038 rad/s

2) kinetic energy loss = 0.24J

Explanation:

1) This is a case of conservation of angular momentum.

The initial angular momentum must be equal to the final angular momentum

Initial angular momentum = I x w

Where I = moment of inertia, and

w = angular momentum.

Initial angular momentum = 0.0711 x 4.53 = 0.322 kg-m2-rad/s

After addition of ring, moment of inertia becomes,

0.0711 + 0.0353 = 0.106 kg-m2

Therefore, final angular momentum will be

0.106 x Wf

Where Wf = final common angular velocity

Equating the two angular momentum we have

0.322 = 0.106Wf

Wf = 0.322/0.106 = 3.038 rad/s

2) KE = 1/2 x I x w^2

Initial KE = 1/2 x 0.0711 x 4.53^2

= 0.729 J

Final KE = 1/2 x 0.106 x 3.038^2

= 0.489 J

Loss in KE = 0.729 - 0.489 = 0.24 J

5 0

4 years ago