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2 years ago

A common wire type is ______ conductor.

Physics

1 answer:

belka [17]2 years ago

5 0

Its c because i look it up on quizlet

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A person throws a stone from the corner edge of a building. The stone's initial velocity is 28.0 m/s directed at 43.0° above the

Naya [18.7K]

The stone's acceleration, velocity, and position vectors at time $t$ are

$\mathbf a(t)=-g\,\mathbf j$

$\mathbf v(t)=v_{i,x}\,\mathbf i+\left(v_{i,y}-gt\right)\,\mathbf j$

$\mathbf r(t)=v_{i,x}t\,\mathbf i+\left(y_i+v_{i,y}t-\dfrac g2t^2\right)\,\mathbf j$

where

$g=9.80\dfrac{\rm m}{\mathrm s^2}$

$v_{i,x}=\left(28.0\dfrac{\rm m}{\rm s}\right)\cos43.0^\circ\approx20.478\dfrac{\rm m}{\rm s}$

$v_{i,y}=\left(28.0\dfrac{\rm m}{\rm s}\right)\sin43.0^\circ\approx19.096\dfrac{\rm m}{\rm s}$

and $y_i$ is the height of the building and initial height of the rock.

(a) After 6.1 s, the stone has a height of 5 m. Set the vertical component $(\mathbf j)$ of the position vector to 5 m and solve for $y_i$ :

$5\,\mathrm m=y_i+\left(19.096\dfrac{\rm m}{\rm s}\right)(6.1\,\mathrm s)-\dfrac12\left(9.80\dfrac{\rm m}{\mathrm s^2}\right)(6.1\,\mathrm s)^2$

$\implies\boxed{y_i\approx70.8\,\mathrm m}$

(b) Evaluate the horizontal component $(\mathbf i)$ of the position vector when $t=6.1\,\mathrm s$ :

$\left(20.478\dfrac{\rm m}{\rm s}\right)(6.1\,\mathrm s)\approx\boxed{124.92\,\mathrm m}$

(c) The rock's velocity vector has a constant horizontal component, so that

$v_{f,x}=v_{i,x}\approx20.478\dfrac{\rm m}{\rm s}$

where $v_{f,x}$

For the vertical component, recall the formula,

${v_{f,y}}^2-{v_{i,y}}^2=2a\Delta y$

where $v_{i,y}$ and $v_{f,y}$ are the initial and final velocities, $a$ is the acceleration, and $\Delta y$ is the change in height.

When the rock hits the ground, it will have height $y_f=0$ . It's thrown from a height of $y_i$ , so $\Delta y=-y_i$ . The rock is effectively in freefall, so $a=-g$ . Solve for $v_{f,y}$ :

${v_{f,y}}^2-\left(19.096\dfrac{\rm m}{\rm s}\right)^2=2(-g)(-124.92\,\mathrm m)$

$\implies v_{f,y}\approx-53.039\dfrac{\rm m}{\rm s}$

(where we took the negative square root because we know that $v_{f,y}$ points in the downward direction)

So at the moment the rock hits the ground, its velocity vector is

$\mathbf v_f=\left(20.478\dfrac{\rm m}{\rm s}\right)\,\mathbf i+\left(-53.039\dfrac{\rm m}{\rm s}\right)\,\mathbf j$

which has a magnitude of

$\|\mathbf v_f\|=\sqrt{\left(20.478\dfrac{\rm m}{\rm s}\right)^2+\left(-53.039\dfrac{\rm m}{\rm s}\right)^2}\approx\boxed{56.855\dfrac{\rm m}{\rm s}}$

(d) The acceleration vector stays constant throughout, so

$\mathbf a(t)=\boxed{-g\,\mathbf j}$

4 0

3 years ago

a person hears an echo from the top of a tower , 2.2 second after the sound is produced.how far away is the tower from the perso

bekas [8.4K]

Answer:

730.4 m

Explanation:

The sound waves travels with a uniform motion (=constant velocity), therefore we can calculate the distance it travels using the formula:

$d=vt$

where

d is the distance

v is the speed of the sound wave

t is the time taken

In this problem we have:

v = 332 m/s is the speed of sound in air

t = 2.2 s is the time elapsed

Therefore, the distance between the tower and the person is

$d=(332)(2.2)=730.4 m$

5 0

3 years ago

Hi how do i run faster

Andrei [34K]

Answer:

Creatine is a great option , its not gonna help long term running ; but a great boost when you first start the run/jog.

Now to run faster you have to build great endurance and that is done through constant exercise running and stamina work outs such as sports , sprints calistetics etc.

Explanation:

Its not a simple 1 time thing and your suddenly , it takes drive and motivation !

Hope i was able to help you out ! Have a great day :)

7 0

2 years ago

Describe the position of the sun, moon, and earth during a new moon and a full moon.

Gennadij [26K]

Answer:

* he new moon phase when the position is Sun - Moon - Earth,

* have of the Full Moon when the position is Sun - Earth - Moon,

*All the phases of the moon are governed by the movement of the Moon around the Earth.

Explanation:

In the solar system, the planets revolve around the sun, which is much more massive, in the case of the Earth it is more massive than its satellite, therefore the Moon revolves around the Earth in a period of approximately 28 days.

It is said that the moon is in the new moon phase when the position is Sun - Moon - Earth, so the moon cannot be seen

It is in the phase of the Full Moon when the position is

Sun - Earth - Moon, in this case the moon can be observed by the light reflected from it.

All the phases of the moon are governed by the movement of the Moon around the Earth.

8 0

3 years ago

Find the intensity of a 55 dB sound given I 0=10^-12W/m^2

MakcuM [25]

Answer:

3.16 × $10^{-7}$ W/ $m^{2}$