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Sunny_sXe [5.5K]

3 years ago

8

A book falls off the desk and makes a sound when it hits the floor. The sound wave that travels through the air is

2 answers:

Nat2105 [25]3 years ago

8 0

The sound wave that travels through the air is a longitudinal mechanical compression wave. The energy it carries comes from the kinetic energy of the fallen book.

Andreas93 [3]3 years ago

6 0

The sound wave that travel through the are is called the <em>amplitude</em> or <em>frequency you can use either of them because there both correct.</em>

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An ice-skater is moving at a constant velocity across an icy pond, The skater throws a snowball directly ahead.

Murljashka [212]

Answer:

(D) It is equal to the original velocity of the skater.

Explanation:

The velocity of the center of mass of a system is

$\vec{v}_{cm} = \frac{m1\vec{v}_1 + m_2\vec{v}_2}{m_1 + m_2}$

The velocity of the center of mass is constant if there is no external force, because the total momentum of the whole system is conserved.

So, before the snowball is thrown, the velocity of the center of mass is equal to that of the skater. This velocity will always be equal to the velocity of the center of mass of the system.

6 0

4 years ago

A particle that is moving along a straight line accelerates from 40 cm/s to 20 cm/s in 5.0 s and then has a constant acceleratio

Marrrta [24]

Answer:

Average speed, $v_{avg}=43.33\ \rm cm/s$

Explanation:

Given:

Initial speed, u=40 cm/s
final speed , v=20 cm/s
Time taken, t=5 s

<u>First case</u>

Using equation of motion we have

$2as=v^2-u^2\\2as=20^2-40^2\\as=-600\\$

Now using,

$v=u +at\\20=40+a\times5\\a=-4\ \rm cm/s^2$

now putting the value of a in first equation we get

$s=150\ \rm cm$

<u>Second case</u>

Acceleration $a=20\ \rm cm/s^2$

Time taken $t=4\ \rm s$

using equation of motion in one Dimension we have

$s=ut+\dfrac{at^2}{2}\\\\s=20\ties 4+\dfrac{20\times 4^2}{2}\\s=240\ \rm cm$

Average speed is equal to total distance travelled per unit total time taken

$v_{avg}=\dfrac{150+240}{5+4}\\v_{avg}=43.33\ \rm cm/s$

4 0

4 years ago

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A mole runs 10 meters due East, then runs 9 meters due South, then runs 3 meters due North. The mole then burrows 2 meters down

Vladimir [108]

Let the directions are defined by vectors as following

East = + x direction

West = - x direction

North = + y direction

South = - y direction

upwards = + z direction

downwards = - z direction

So here we are given that it moves

1). 10 m East

2). 9 m South

3). 3 m North

4). 2 m down

So we can write it as

$d_1 = 10 \hat i$

$d_2 = 9 (-\hat j)$

$d_3 = 3 \hat j$

$d_4 = 2 (-\hat k)$

Now total displacement will be given as

$d = d_1 + d_2 + d_3 +d_4$

$d = 10 \hat i - 9 \hat j + 3 \hat j - 2 \hat k$

$d = 10 \hat i - 6 \hat j - 2 \hat k$

now the magnitude of the displacement will be

$d = \sqrt{10^2 + 6^2 + 2^2}$

$d = 11.8 m$

so the magnitude of displacement will be 11.8 m

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3 years ago

I lean against a wall, applying force. Which could be described as the “reaction force?”

VARVARA [1.3K]

The answer is B The Wall Force Against Me

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4 years ago

In the Arctic, caribou and musk ox eat different kinds of plants, but the plants they eat typically grow in the same area. There

gtnhenbr [62]

Wait I’m confused of the question explain plz

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3 years ago

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