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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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Consider a father pushing a child on a playground merry-go-round. The system has a moment of inertia of 84.4 kg.m^2. The father

Sophie [7]

Answer:

Explanation:

Given that:

the initial angular velocity $\omega_o = 0$

angular acceleration $\alpha$ = 4.44 rad/s²

Using the formula:

$\omega = \omega_o+ \alpha t$

Making t the subject of the formula:

$t= \dfrac{\omega- \omega_o}{ \alpha }$

where;

$\omega = 1.53 \ rad/s^2$

∴

$t= \dfrac{1.53-0}{4.44 }$

t = 0.345 s

Using the formula:

$\omega ^2 = \omega _o^2 + 2 \alpha \theta$

here;

$\theta$ = angular displacement

∴

$\theta = \dfrac{\omega^2 - \omega_o^2}{2 \alpha }$

$\theta = \dfrac{(1.53)^2 -0^2}{2 (4.44) }$

$\theta =0.264 \ rad$

Recall that:

2π rad = 1 revolution

Then;

0.264 rad = (x) revolution

$x = \dfrac{0.264 \times 1}{2 \pi}$

x = 0.042 revolutions

Here; force = 270 N

radius = 1.20 m

The torque = F * r

$\tau = 270 \times 1.20 \\ \\ \tau = 324 \ Nm$

However;

From the moment of inertia;

$Torque( \tau) = I \alpha \\ \\ Since( I \alpha) = 324 \ Nm. \\ \\ Then; \\ \\ \alpha= \dfrac{324}{I}$

given that;

I = 84.4 kg.m²

$\alpha= \dfrac{324}{84.4} \\ \\ \alpha=3.84 \ rad/s^2$

For re-tardation; $\alpha=-3.84 \ rad/s^2$

Using the equation

$t= \dfrac{\omega- \omega_o}{ \alpha }$

$t= \dfrac{0-1.53}{ -3.84 }$

$t= \dfrac{1.53}{ 3.84 }$

t = 0.398s

The required time it takes= 0.398s

5 0

2 years ago

An object experiences an acceleration of -6.8 m/s2. As a result, it accelerates from 54 m/s to a complete stop. How much dista

inessss [21]

Answer:

The distance traveled during its acceleration, d = 214.38 m

Explanation:

Given,

The object's acceleration, a = -6.8 m/s²

The initial speed of the object, u = 54 m/s

The final speed of the object, v = 0

The acceleration of the object is given by the formula,

a = (v - u) / t m/s²

∴ t = (v - u) / a

= (0 - 54) / (-6.8)

= 7.94 s

The average velocity of the object,

V = (54 + 0)/2

= 27 m/s

The displacement of the object,

d = V x t meter

= 27 x 7.94

= 214.38 m

Hence, the distance the object traveled during that acceleration is, a = 214.38 m

3 0

3 years ago

An electron is traveling with initial kinetic energy K in a uniform electric field. The electron comes to rest momentarily after

KatRina [158]

Answer:

$E = kQs/r.r$

Explanation:

Where E is the magnitude of electric field...

k is called Columb's Constant. It has a value of 8.99 x 109 N m2/C2.

Qs is the magnitude of the source charge...

and r is the magnitude of distance between source and target...

(When electron comes to rest Δt the magnitude of Electric field E become zero momentarily but later achieves the maximum value...)

5 0

3 years ago

What net force is required to accelerate a car at a rate of 2m/s^2 if the car has a mass of 3,000kg? plus explanation with equat

Vinvika [58]

Answer:

Explanation:

The force acting on an object given it's mass and acceleration can be found by using the formula

force = mass × acceleration

From the question

mass = 3000 kg

acceleration = 2 m/s²

We have

force = 3000 × 2 = 6000

We have the final answer as

Hope this helps you

3 0

2 years ago

3. A wye-connected load has a voltage of 480 V applied to it. What is the voltage dropped across each phase?

ZanzabumX [31]

Answer:

$E_s = 277.13V$

Explanation:

Given

$Load\ Voltage = 480V$

Required

Determine the voltage dropped in each stage.

The relation between the load voltage and the voltage dropped in each stage is

$E_l = E_s * \sqrt3$

Where

$E_l = 480$

So, we have:

$480 = E_s * \sqrt3$

Solve for $E_s$

$E_s = \frac{480}{\sqrt3}$

$E_s = \frac{480}{1.73205080757}$

$E_s = 277.128129211$

$E_s = 277.13V$

<em>Hence;</em>

<em>The voltage dropped at each phase is approximately 277.13V</em>

5 0

3 years ago