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3 years ago

Can a chemical change be undone?

Physics

2 answers:

Ksivusya [100]3 years ago

6 0

Answer:

Explanation:

because it will bind together in the molecular level

Zigmanuir [339]3 years ago

3 0

Because chemical changes result in different substances, they often cannot be undone. Some chemical changes can be reversed, but only by other chemical changes.

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A cannonball is fired in such a way

Goryan [66]

Answer:

θ = 53.13° above horizontal

Explanation:

Ignore air resistance.

The time the ball takes to reach its max height will equal the time to travel half the max range R.

√(2h/g) = (R/2)/vcosθ

vsinθ/g = R/2vcosθ

2v²sinθcosθ = Rg

2v²sinθcosθ = 3hg

v² = u² + 2gh

0² = v²sin²θ + 2gh

v²sin²θ = 2gh

v² = 2gh/sin²θ

2v²sinθcosθ = 3hg

(2gh/sin²θ)2sinθcosθ = 3hg

(2/sinθ)2cosθ = 3

cotθ = 3/4

θ = 53.130

5 0

3 years ago

A baseball is thrown straight up. the drag force is proportional to v2. part a in terms of g, what is the y-component of the bal

steposvetlana [31]

At the position of terminal speed the net acceleration of the ball will become zero

As we know that terminal speed will always reach when net force on the ball is zero and its speed will become constant.

So here at this position we can say

$F_d = F_g$

$kv^2 = mg$

$v =\sqrt{\frac{mg}{k}}$

now when ball is moving at half of the terminal speed in upward direction then net force on the ball in downwards direction will be

$F_{net} = mg + F_d$

$F_{net} = mg + kv^2$

here speed of the ball is half of the terminal speed

$v = \frac{1}{2}*\sqrt{\frac{mg}{k}}$

then we have

$F_{net} = mg + k*\frac{mg}{4k}$

$F_{net} = \frac{5mg}{4}$

now acceleration will be given as

$a = \frac{F_{net}}{m}$

now we have

$a = \frac{5g}{4}$

$a = 12.25 m/s^2$ downwards

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4 years ago

PLEASE HELP BALANCED AND UNBALANCED FORCE QUESTION

Illusion [34]

Answer:

Explanation:

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4 years ago

Relation of Kilometre and mile

Alja [10]

Answer:

1km = o.621371 mile

Explanation:

1.609 kilometers equal 1 mile. The kilometer is a unit of measurement, as is the mille. However, a mile is longer than a kilometer.

5 0

3 years ago

Read 2 more answers

The wavelength of red helium-neon laser light in air is 632.8 nm.

e-lub [12.9K]

(a) $4.74\cdot 10^14 Hz$

The frequency of an electromagnetic wave is given by:

$f=\frac{c}{\lambda}$

where

$c=3.0\cdot 10^8 m/s$ is the speed of the wave in a vacuum (speed of light)

$\lambda$ is the wavelength

In this problem, we have laser light with wavelength

$\lambda=632.8 nm=6.33\cdot 10^{-7} m$ . Substituting into the formula, we find its frequency:

$f=\frac{3.0\cdot 10^8 m/s}{6.33\cdot 10^{-7} m}=4.74\cdot 10^14 Hz$

(b) 427.6 nm

The wavelength of an electromagnetic wave in a medium is given by:

$\lambda=\frac{\lambda_0}{n}$

where

$\lambda_0$ is the original wavelength in a vacuum (approximately equal to that in air)

$n$ is the index of refraction of the medium

In this problem, we have

$\lambda_0=632.8 nm$

n = 1.48 (index of refraction of glass)

Substituting into the formula,

$\lambda=\frac{632.8 nm}{1.48}=427.6 nm$

(c) $2.03\cdot 10^8 m/s$

The speed of an electromagnetic wave in a medium is

$v=\frac{c}{n}$

where c is the speed of light in a vacuum and n is the refractive index of the medium.

Since in this problem n=1.48, we find

$v=\frac{3\cdot 10^8 m/s}{1.48}=2.03\cdot 10^8 m/s$

3 0

4 years ago

Can a chemical change be undone?​

Can a chemical change be undone?