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2 years ago

Which of the following about Dalton's theory of matter is true?

1 answer:

6 0

D.Atoms can be divided into smaller parts.

Dalton's atomic theory was the first complete attempt to describe allmatter in terms of atoms and their properties. Dalton based his theory on the law of conservation of mass and the law of constant composition. The first part of his theory states that allmatter is made of atoms, which are indivisible.

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A lifeguard on a beach observes that waves have a speed of 7 m/s and a distance of 4.6m between wave crests. what is the period

Pepsi [2]

Answer:

0.657 seconds

Explanation:

speed of wave= wavelength / time period

time period= wavelength / speed

= 4.6/7

=0.657 sec

4 0

3 years ago

Two polarizers A and B are aligned so that their transmission axes are vertical and horizontal, respectively. A third polarizer

Reptile [31]

Answer:

Explanation:

Let the angle between the first polariser and the second polariser axis is θ.

By using of law of Malus

(a)

Let the intensity of light coming out from the first polariser is I'

$I' = I_{0}Cos^{2}\theta$ .... (1)

Now the angle between the transmission axis of the second and the third polariser is 90 - θ. Let the intensity of light coming out from the third polariser is I''.

By the law of Malus

$I'' = I'Cos^{2}\left ( 90-\theta \right )$

So,

$I'' = I_{0}Cos^{2}\theta Cos^{2}\left ( 90-\theta \right )$

$I'' = I_{0}Cos^{2}\theta Sin^{2}\theta$

$I'' = \frac{I_{0}}{4}Sin^{2}2\theta$

(b)

Now differentiate with respect to θ.

$I'' = \frac{I_{0}}{4}\times 2 \times 2 \times Sin2\theta \times Cos 2\theta$

$I'' = \frac{I_{0}}{2}\times Sin 4\theta$

7 0

3 years ago

In a laboratory, it is often convenient to make measurements in centimeters and grams, but SI units are needed for calculations.

zheka24 [161]

Answer:

(a) 0.92 cm= 0.092 m.

(b) 141.64 g=0.14164 kg.

(d) 63.6 g/cm³= 63600 kg/m³

Explanation:

The International System of Units, abbreviated S.I., also called the International System of Measurements is a system of measurements in which its units are based on fundamental physical phenomena. The units of the S.I. They are the international reference for the indications of all measuring instruments.

The International System of Units (SI) arose from the need to unify and give coherence to a great variety of unit subsystems.

The International System of Units consists of seven basic units, also called fundamental units, which define the corresponding fundamental physical quantities and which allow any physical quantity to be expressed in terms or as a combination of them. The fundamental physical quantities are complemented by two more physical quantities, called supplementary ones.

By combining the basic units, the other units are obtained, called units derived from the International System, and which allow defining any physical quantity.

(a) The SI unit of length is the meter. Being 1 cm = 0.01 m, then 0.92 cm= 0.092 m.

(b) The SI unit of mass is kg. Being 1 g = 0.001 kg, then 141.64 g=0.14164 kg.

(d) Being 1 g/cm³= 1000 kg/m³, then 63.6 g/cm³= 63600 kg/m³

3 0

3 years ago

According to newton, doubling the distance between two interacting objects:

Furkat [3]

Answer:

So as two objects are separated from each other, the force of gravitational attraction between them also decreases. If the separation distance between two objects is doubled (increased by a factor of 2), then the force of gravitational attraction is decreased by a factor of 4 (2 raised to the second power).

Explanation:

hope his helps

8 0

2 years ago

Rank the following meteorites in terms of their age, from youngest to oldest:1) a meteorite containing 500 238U isotopes and 100

satela [25.4K]

Answer:

Explanation:

When 238U which is radioactive turns into 206Pb , it becomes stable and no further disintegration is done . Hence in the initial period ratio of 238U undecayed and 206Pb formed will be very high because no of atoms of 238U in the beginning will be very high. Gradually number of 238U undecayed will go down and number of 206Pb formed will go up . In this way the ratio of 238U and 206Pb in the mixture will gradually reduce to be equal to one or even less than one .

In the given option we shall calculate their raio

1 ) ratio of 238U and 206Pb = 5

2 ) ratio of 238U and 206Pb = 4

3 )ratio of 238U and 206Pb = 1

4 ) ratio of 238U and 206Pb = 20

5 )ratio of 238U and 206Pb = 3

lowest ratio is 1 , hence this sample will be oldest.

Ranking from youngest to oldest

4 , 1 , 2 , 5 , 3 .

4 0

3 years ago