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3 years ago

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Many scientific discoveries are made by chance. While studying one phenomenon, a scientist may discover a different one. Such wa

s the case when William Herschel discovered the planet Uranus in 1781. Herschel was charting faint stars in the sky, when he discovered something that was not a star. How can astronomers tell the difference between a star and a planet

1 answer:

Vedmedyk [2.9K]3 years ago

3 0

Answer:

One simple explanation is that planets move, while stars remained fixed in the sky. You can observe a planet's orbit, but a star will stay in the same position.

Explanation:

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If energy is absorbed because chemical reaction is ______.

melomori [17]

<h2>Answer:</h2>

The reaction is <u>D. endothermic</u>.

<h2>Explanation:</h2>

Absorption or need of energy from surroundings is called endothermic process. Heat is the major common form of energy which is absorbed in this process. In this process, enthaply of reactant is less than the product.

For example, an ice cube placed in the hand for some time starts to melt and it takes energy in the form of heat from the hand. This process always requires energy because of the breaking of existing and formation of new chemical bonds.

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3 years ago

Limestone cave can develop when Limestone rock is weathered. The weathering of the rock leaves an empty space that forms the cav

Ymorist [56]

Answer:

Wind blowing across the surface eroded the limestone.

Explanation:

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3 years ago

Read 2 more answers

As the wavelength increases, the frequency (2 points) decreases and energy decreases. increases and energy increases. decreases

frozen [14]

Bohr's equation for the change in energy is
$\Delta E= \frac{hc}{\lambda}$
where
h = Planck's constant
c == the velocity of light
λ = wavelength.

The velocity is related to wavelength and frequency, f, by
c = fλ

Let us examine the given answers on the basis of the given equations.

a. As λ increases, f decreases and ΔE decreases.
TRUE

b. As λ increases, f increases and ΔE increases.
FALSE

c. As λ increases, f increases and ΔE decreases.
FALSE

Answer:
As the wavelength increases, the frequency decreases and energy decreases.

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4 years ago

Read 2 more answers

A portable basketball set has a base and a post arrangement. The post arrangement consists of a post, backboard, hoop and net. T

Ray Of Light [21]

The rotational equilibrium condition allows finding the response to the minimum force of the wind and what happens when changing the water for sand, in the system

a) The minimum force of the wind that turns the system is Fw = 17.64 N

b) The system resists much greater forces because the base has more mass

Newton's Second Law can be applied to rotational motion in this case when the angular acceleration is zero we have the special case of rotational equilibrium

Σ τ = 0

Where τ is the torque

The reference system is a coordinate system with respect to which the torques are measured, in this case we will fix the system at the turning point, the junction of the base and the pole, we will assume that the counterclockwise rotations are positive.

For the torque the distance used is the perpendicular distance from the direction of the force to the axis of rotation, let's find this distance for each force

Wind force

cos 15 = $\frac{y_w}{2.35}$

$y_w$ = 2.35 cos 15

Post Weight

sin 15 = $\frac{x_p}{2.00}$

xp = 2.0 sin 15

Base weight

cos (90-15) = $\frac{x_b}{0.25}$

xB = 0.25 cos 75

Let's substitute in the rotational equilibrium equation

$F_w \ y_w + W_p \ x_p - W_b \ x_b = 0$

a) To calculate the minimum wind force we substitute the given values

They indicate the weight of the post is $W_p$ = 26.0 N and the weight of the base with water is $W_b$ = 810 N

$F_w = \frac{W_b \ x_b - W_p \ x_p }{y_w}$

$F_w = \frac{W_b \ 0.25 cos75 \ - W_p \ 2 sin 15}{2.35 cos 15}$

Let's calculate

$F_w = \frac{810 \ 0.25 \ cos75 \ - 26.0 \ 2 \ sin 15}{2.35 cos15}\\F_w = \frac{52.41 - 10.30}{2.3699}$

$F_w$ = 17.64 N

b) The water is exchanged for sand.

In this case, as the density of the sand is greater than that of the water, the base will have more weight, so it will resist stronger winds before turning over.

Using the rotational equilibrium condition we can find the response to the minimum force of the wind and what happens when changing the water for sand,

a) the minimum force of the wind that turns the system is Fw = 17.64 N

b) the system resists much greater forces because the base has more mass

Learn more here: brainly.com/question/7031958

3 0

3 years ago

A child and sled with a combined mass of 58.0 kg slide down a frictionless slope. If the sled starts from rest and has a speed o

erma4kov [3.2K]

Answer:

The height is $h = 0.5224 \ m$

Explanation:

From the question we are told that

The combined mass of the child and the sled is $m = 58.0 \ kg$

The speed of the sled is $u = 3.20 \ m/s$

Generally applying SOHCAHTOA on the slope which the combined mass is down from

Here the length of the slope(L) where the combined mass slides through is the hypotenuses

while the height(h) of the height of the slope is the opposite

Hence from SOHCAHTOA

$sin (\theta) = \frac{h}{L}$

=> $Lsin(\theta) = h$

Generally from the kinematic equation we have that

$v^2 = u^2 + 2aL$

Here the u is the initial velocity of the combined mass which is zero since it started from rest

and a is the acceleration of the combined mass which is mathematically evaluated as

$a = g * sin (\theta )$

$v^2 = u^2 + 2 * g * sin (\theta )L$

=> $2Lsin(\theta ) = \frac{v^2 - u^2 }{g}$

=> $h = \frac{ v^2 - u^2}{2g}$

=> $h = \frac{ 3.20^2 - 0^2}{2 * 9.8 }$

=> $h = 0.5224 \ m$

6 0

3 years ago