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3 years ago

Find the wavelength of the ultrasonic wave emitted by a bat if it has a frequency of 4.0 * 10^4 Hz.

Physics

2 answers:

Oliga [24]3 years ago

6 0

ultrasonic wave is a type of sound wave. speed of sound in air at room temp is 343m/s.

speed = wavelength * frequency

wavelength = speed / frequency = 343/4*10^4

= 0.00858m

= 8.58mm

morpeh [17]3 years ago

5 0

Remark

You have to pick a velocity for an ultra sound wave. I'm going to take the sound velocity to be 331 m/s in air, because I'm assuming that is what is meant: it is the sound a bat would make once he emits the ultrasound to a microphone like device that receives it. The media through which that happens is air.

Givens

v = 331m/s

f = 4 *10^4 hz

Formula

velocity = wavelength * frequency

v = $\lambda$ *f

331/(4*10^4) = $\lambda$

0.008275 = $\lambda$

8.275*10^-3 = $\lambda$

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Alex swims at an average speed of 4.5 m/s how far does he swim in one minute 24 seconds

Zepler [3.9K]

Answer:

378

Explanation:

60 seconds in one minute

add the 24 seconds

multiply it by 4.5

60 + 24 = 84

4.5 x 84 = 378

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3 years ago

Carmen is heating some water and trying to measure the temperature of water using a Celsius thermometer. Which measurement can s

andrew-mc [135]

100° C she can expect once the water begins to boil.

Option: B

Explanation:

The boiling point for water at 1 pressure atmosphere of sea level is 212 ° F or 100 ° C. That value isn't a fixed. Water's boiling point is dependent on the ambient pressure, which varies based on elevation. At a lower temperature, water boils as one gains altitude like getting higher on a hill, and boils at a higher temperature if one increases the atmospheric pressure of returning to or below sea level.

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3 years ago

Read 2 more answers

How high does a rocket have to go above Earth's surface before its weight is half of what it is on Earth?

Contact [7]

Answer:

$h=1.6\times 10^6\ m$

Explanation:

As we know that the acceleration due to gravity decreases with height.

At certain height it will get to the half of its value on the surface of the earth.

As we know that the weight on the surface of the earth is given as:

$w=m.g$

where:

m = mass of the object

g = acceleration due to gravity of the substance

Since mass of the substance is constant so the variation is weight is possible only due to change in the acceleration due to gravity.

We know that the variation of the acceleration due gravity with height is given as:

$g_{_h}=g\times (1-\frac{2h}{R} )$

where:

$g_{_h}=$ value to acceleration due to gravity at height h

g = acceleration due to gravity at the earth's surface

h = height of the object

R = radius of the earth = $6400\ km$

according to question the weight becomes half, so,:

$4.9=9.8\times (1-\frac{2h}{6400\times10^3} )$

$h=1.6\times 10^6\ m$ is the height a rocket has to go above Earth's surface before its weight is half of what it is on Earth.

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3 years ago

A Ferris wheel with a 15-m radius makes three complete revolutions in one minute about its horizontal axis. What is the magnitud

Kay [80]

Answer:

$1.48 m/s^2$ , upward

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The passenger on the wheel experiences a centripetal acceleration, which is the one that keeps him in a circular motion.

The direction of this acceleration is always towards the centre of the circular trajectory: so when the passenger is at the lowest point of the ride, the acceleration is upward.

Concerning the magnitude, it is given by

$a=\omega^2 r$

where

$\omega$ is the angular velocity

r = 15 m is the radius

We need to find the angular velocity; we know that the wheel completes 3 revolutions in one minute. Each revolution corresponds to an angle of $2\pi$ rad, so the total angular displacement is

$\theta = 3 \cdot 2\pi = 6\pi$ rad

And the time is

$t = 1 min = 60 s$

So the angular velocity is

$\omega = \frac{6\pi}{60 s}=0.314 rad/s$

And substituting into the equation of the acceleration,

$a=(0.314)^2(15)=1.48 m/s^2$

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3 years ago

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gladu [14]

Answer:

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The wave property of the electrons can be observed with the help of experiment.

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