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3 years ago

Which force requires contact

Physics

2 answers:

guapka [62]3 years ago

6 0

Tension force? There ay be more than one, but that is all I can currently think of.

jekas [21]3 years ago

5 0

Gravity?????????? or maybe like any object

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Radon-222 ( 222/86 Rn) is a radioactive gas with a half-life of 3.82 days. A gas sample contains 4.1 e 8 radon atoms initially.

kow [346]

Answer :

(a) The number of radon atoms will remain after 12 days is, $4.67\times 10^7$

(b) The number of radon nuclei have decayed by this time will be, $3.6\times 10^8$

Explanation :

For part (a) :

Half-life = 3.82 days

First we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{3.82\text{ days}}$

$k=1.81\times 10^{-1}\text{ days}^{-1}$

Now we have to calculate the number of radon atoms will remain after 12 days.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant = $1.81\times 10^{-1}\text{ days}^{-1}$

t = time passed by the sample = 12 days

a = initially number of radon atoms = $4.1\times 10^8$

a - x = number of radon atoms left = ?

Now put all the given values in above equation, we get

$12=\frac{2.303}{1.81\times 10^{-1}}\log\frac{4.1\times 10^8}{a-x}$

$a-x=4.67\times 10^7$

Thus, the number of radon atoms will remain after 12 days is, $4.67\times 10^7$

For part (b) :

Now we have to calculate the number of radon nuclei will have decayed by this time.

The number of radon nuclei have decayed = Initial number of radon atoms - Number of radon atoms left

The number of radon nuclei have decayed = $(4.1\times 10^8)-(4.67\times 10^7)$

The number of radon nuclei have decayed = $3.6\times 10^8$

Thus, the number of radon nuclei have decayed by this time will be, $3.6\times 10^8$

5 0

3 years ago

What ion is a proton also known as ??

sattari [20]

It is an Hydrogen Ion

4 0

4 years ago

Read 2 more answers

A layer of ethyl alcohol (n = 1.361) is on top of water (n = 1.333). To the nearest degree, at what angle relative to the normal

AleksAgata [21]

Answer:

a. 78 degree

Explanation:

According to Snell's Law, we have:

(ni)(Sin θi) = (nr)(Sin θr)

where,

ni = Refractive index of medium on which light is incident

ni = Refractive index of ethyl alcohol = 1.361

nr = Refractive index of medium from which light is refracted

nr = Refractive index of ethyl alcohol = 1.333

θi = Angle of Incidence

θr = Angle of refraction

So, the Angle of Incidence is know as the Critical Angle (θc), when the refracted angle becomes 90°. This is the case of total internal reflection. That is:

θi = θc

when, θr = 90°

Therefore, Snell's Law becomes:

(1.361)(Sin θc) = (1.333)(Sin 90°)

Sin θc = 1.333/1.361

θc = Sin⁻¹ (0.9794)

θc = 78.35° = 78° (Approximately)

Therefore, correct answer will be:

a. 78 degree

8 0

3 years ago

An experiment in which alpha particles were used to bombard thin sheets of gold foil led to the conclusion that an atom is compo

fiasKO [112]

Answer:

a small dense nucleus with positive charge and the nucleus is surrounding by orbiting electrons.

Explanation:

An experiment in which alpha particles were used to bombard thin sheets of gold foil led to the conclusion that an atom is composed mostly of a small dense nucleus with positive charge and the nucleus is surrounding by orbiting electrons.

8 0

3 years ago

Why will interference occur

den301095 [7]

Two waves interfere when they run into each other.

The barrier reflects waves that run straight into it. It acts as a wave source and sends wave pulses back up the page towards the incoming waves.

Imagine a loose string tied to a wall. Someone sends two consecutive pulses along the string towards the wall. The first pulse gets reflected right away. It will travel backward towards the person holding the string. Along its way, it will run into the second pulse. The two pulses will interfere. The wall will make the reflected pulse out of phase with the second one. They will end up creating a destructive interference.

So is the case with the water waves running into the barrier. The barrier will send incoming waves back toward where they came from. Reflected waves interfere with incoming ones.

7 0

3 years ago