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2 years ago

How is the frequency of a wave measured?

Physics

2 answers:

Lapatulllka [165]2 years ago

5 0

It’s A, the actual image of the wave is supposed to show how it bounces back and forth with vibrations.

lianna [129]2 years ago

4 0

D. How high do the sound waves go

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An elevator is moving downward when someone presses the emergency stop button. The elevator comes to rest a short time later. Gi

OLga [1]

Answer:

<em>Answer: - , + </em>

Explanation:

<u>Velocity and Acceleration </u>

In general terms, velocity and acceleration in the plane are both vectors with two components. They don't have 'sign' but magnitude and direction. If we know motion is restricted to a simple line, then we can define the positive and negative references.

In vertical motion, the positive reference is commonly pointed upwards, but if we chose the opposite way, the results shouldn't change in magnitude, just their signs. Let's choose like proposed, the positive direction upwards.

Since the elevator was moving downwards, its velocity is negative. When the button is pushed, it continues to move downwards, but slower. Its velocity is still negative.

The acceleration has the same sign as the velocity if it tends to increase the magnitude of the object, and is negative in the opposite case. Let's look at the formula

$\displaystyle a=\frac{v_f-v_o}{t}$

In this case, $v_f=0$ because the elevator will eventually stop, and $v_o$ is negative. It means the acceleration is

$\displaystyle a=\frac{-v_o}{t}$

It results in a positive value

$\boxed{Answer: -,+}$

Note: If we chose the opposite references, then the answer would be: +,-

5 0

3 years ago

An open 1-m-diameter tank contains water at a depth of 0.7 m when at rest. As the tank is rotated about its vertical axis the ce

Mamont248 [21]

Answer:

Explanation:

To find the angular velocity of the tank at which the bottom of the tank is exposed

From the information given:

At rest, the initial volume of the tank is:

$V_i = \pi R^2 h_i --- (1)$

where;

height h which is the height for the free surface in a rotating tank is expressed as:

$h = \dfrac{\omega^2 r^2}{2g} + C$

at the bottom surface of the tank;

r = 0, h = 0

∴

$h = \dfrac{\omega^2 r^2}{2g} + C$

0 = 0 + C

C = 0

Thus; the free surface height in a rotating tank is:

$h=\dfrac{\omega^2 r^2}{2g} --- (2)$

Now; the volume of the water when the tank is rotating is:

dV = 2π × r × h × dr

Taking the integral on both sides;

$\int \limits ^{V_f}_{0} \ dV = \int \limits ^R_0 \times 2 \pi \times r \times h \ dr$

replacing the value of h in equation (2); we have:

$V_f} = \int \limits ^R_0 \times 2 \pi \times r \times ( \dfrac{\omega ^2 r^2}{2g} ) \ dr$

$V_f = \dfrac{ \pi \omega ^2}{g} \int \limits ^R_0 \ r^3 \ dr$

$V_f = \dfrac{ \pi \omega ^2}{g} \Big [ \dfrac{r^4}{4} \Big]^R_0$

$V_f = \dfrac{ \pi \omega ^2}{g} \Big [ \dfrac{R^4}{4} \Big] --- (3)$

Since the volume of the water when it is at rest and when the angular speed rotates at an angular speed is equal.

Then $V_f = V_i$

Replacing equation (1) and (3)

$\dfrac{\pi \omega^2}{g}( \dfrac{R^4}{4}) = \pi R^2 h_i$

$\omega^2 = \dfrac{4g \times h_i }{R^2}$

$\omega =\sqrt{ \dfrac{4g \times h_i }{R^2}}$

$\omega = \sqrt{\dfrac{4 \times 9.81 \ m/s^2 \times 0.7 \ m}{(0.5)^2} }$

$\omega = \sqrt{109.87 }$

$\mathbf{\omega = 10.48 \ rad/s}$

Finally, the angular velocity of the tank at which the bottom of the tank is exposed = 10.48 rad/s

6 0

3 years ago

You take a lab battery and, when it isn't connected to a circuit, you measure a voltage of 4.00-V with a voltmeter. You then con

max2010maxim [7]

Answer:

$r = 28.6 ohm$

Explanation:

As we know that when battery is in open circuit then the potential difference of the cell is known as EMF

so EMF is given as

$EMF = 4.00 V$

now when the battery is connected across a resistance of 200 ohm then there is current flowing through the battery

it is given as

$i = \frac{V}{R + r}$

$17.5 \times 10^{-3} = \frac{4}{200 + r}$

$200 + r = 228.6$

$r = 28.6 ohm$

6 0

4 years ago

The maximum current output of a 60 ω circuit is 11 A. What is the rms voltage of the circuit?

Scilla [17]

Answer:

sorry

Explanation:

I dont know the anwser to that one

6 0

3 years ago

You are standing on the bottom of a lake with your torso above water. Which statement is correct?

marishachu [46]

Answer:

c. There is a buoyant force that is proportional to the volume of your body that is below the level of the water.

Explanation:

Buoyancy can be defined as a force which is created by the water displaced by an object.

Simply stated, buoyancy is directly proportional to the amount of water that is being displaced by an object.

Hence, the greater the amount of water an object displaces; the greater is the force of buoyancy pushing the object up.

The buoyancy of an object is given by the formula;

$Fb = pgV$

$But, \; V = Ah$

$Hence, \; Fb = pgAh$

Where;

Fb = buoyant force of a liquid acting on an object.

g = acceleration due to gravity.

p = density of the liquid.

v = volume of the liquid displaced.

h = height of liquid (water) displaced by an object.

A = surface area of the floating object.

The unit of measurement for buoyancy is Newton (N).

In this scenario, you are standing on the bottom of a lake with your torso above water. Thus, there is a buoyant force that is proportional to the volume of your body that is below the level of the water.

3 0

3 years ago