Because water is a very very very very very unusual substance ... It's
the only known substance whose solid form is less dense than its liquid
form near the same temperature.

In other words, water is the only known substance for which a solid lump
of it floats in a liquid glass of it.

If that were not true ... if the behavior of the density of water around its
freezing temperature were the same as the density of all other known
substances ... then life on Earth would be impossible.

Think about that for a while ! Ya gotta admire whoever it was that designed water !

5 0

3 years ago

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Two planets have the same surface gravity, but planet b has twice the radius of planet

vampirchik [111]

Planet A;
m = the mass
Let r = the radius

Planet B:
Let M = the mass
The radius is 2r (twice the radius of planet A)

The surface gravitational acceleration of planets A and B (they have the same surface gravity) are
$g= \frac{Gm}{r^{2}} \, and \, g= \frac{GM}{(2r)^{2}} \\\\ m= \frac{M}{4} \\\\ M=4m$

Answer: The mass of planet B is 4m.

3 0

4 years ago

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A device for training astronauts and jet fighter pilots is designed to rotate the trainee in a horizontal circle of radius 11.0

kvv77 [185]

The velocity of the trainee is 29 m/s or 0.42 rev/s

<h3>Further explanation</h3>

Acceleration is rate of change of velocity.

$\large {\boxed {a = \frac{v - u}{t} } }$

$\large {\boxed {d = \frac{v + u}{2}~t } }$

<em>a = acceleration (m / s²)v = final velocity (m / s)</em>

<em>u = initial velocity (m / s)</em>

<em>t = time taken (s)</em>

<em>d = distance (m)</em>

Centripetal Acceleration of circular motion could be calculated using following formula:

$\large {\boxed {a_s = v^2 / R} }$

<em>a = centripetal acceleration ( m/s² )</em>

<em>v = velocity ( m/s )</em>

<em>R = radius of circle ( m )</em>

Let us now tackle the problem!

<u>Given:</u>

Radius of horizontal circle = R = 11.0 m

Force Felt by the Trainee = F = 7.80w

<u>Unknown:</u>

Velocity of Rotation = v = ?

<u>Solution:</u>

$F = ma$

$F = m\frac{v^2}{R}$

$7.80w = m\frac{v^2}{R}$

$7.80mg = m\frac{v^2}{R}$

$7.80g = \frac{v^2}{R}$

$7.80 \times 9.8 = \frac{v^2}{11.0}$

$v^2 = 840.84$

$v \approx 29 ~m/s$

$\omega = \frac{v}{R}$ → in rad/s

$\omega = \frac{v}{2 \pi R}$ → in rev/s

$\omega = \frac{29}{2 \pi \times 11.0}$

$\omega \approx 0.42 ~ rev/s$

<h3>Learn more</h3>

Velocity of Runner : brainly.com/question/3813437

Kinetic Energy : brainly.com/question/692781

Acceleration : brainly.com/question/2283922

The Speed of Car : brainly.com/question/568302
Uniform Circular Motion : brainly.com/question/2562955
Trajectory Motion : brainly.com/question/8656387

<h3>Answer details</h3>

Grade: High School

Subject: Physics

Chapter: Circular Motion

Keywords: Velocity , Driver , Car , Deceleration , Acceleration , Obstacle , Speed , Time , Rate , Circular , Ball , Centripetal

6 0

4 years ago

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Henrietta is going off to her physics class, jogging down the sidewalk at a speed of 4.15 m/sm/s. Her husband Bruce suddenly rea

Darya [45]

Answer:

Explanation:

Distance travelled by Henrietta in 5.5 s = 4.15 x 5.5 = 22.825 m .

Time taken by lunch of bagels to fall vertically by 55.2 m . Let it be t .

s = ut + 1/2 g t²

55.2 = 0 + .5 x 9.8 x t²

t² = 11.26

t = 3.356 s

By the time the lunch of bagels touches the hand of Henrietta , she would have travelled further by distance

s = 3.356 x 4.15 = 13.9 m

She is now at distance of 22.825 + 13.9 = 36.725 m from window .

So lunch of bagels must travel a horizontal distance of 36.725 m in 3.356 s which the time of fall of bagel .

Speed of bagel = distance / time

= 36.725 / 3.356

= 10.94 m /s

b )

Henrietta is 36.725 m from window at the time when she catches the bangel.

6 0

3 years ago