Which expression correctly describes energy using SI units

The mass of a glass beaker is known to be 24.2 g. Approximately 5 mL of water are added, and the mass of the beaker and water is

Kamila [148]

Answer: 2 significant figures in 6.4

Explanation:

Significant figures : The figures in a number which express the value -the magnitude of a quantity to a specific degree of accuracy is known as significant digits.

Rules for significant figures:

Digits from 1 to 9 are always significant and have infinite number of significant figures.

All non-zero numbers are always significant. For example: 654, 6.54 and 65.4 all have three significant figures.

All zero’s between integers are always significant. For example: 5005, 5.005 and 50.05 all have four significant figures.

All zero’s preceding the first integers are never significant. For example: 0.0078 has two significant figures.

All zero’s after the decimal point are always significant. For example: 4.500, 45.00 and 450.0 all have four significant figures.

Mass of beaker = 24.2 g

Mass of beaker + mass of water = 30.625 g

Mass of water = 30.625 - Mass of beaker = 30.625 - 24.2 = 6.4g

The rule apply for the addition and subtraction is :

The answer would contain same number of decimal places as there are in the least precise number present.

Thus there are 2 significant figures in mass of water which is 6.4 grams.

7 0

3 years ago

Swings are usually made out of materials that do not conduct heat easily, so that children will not burn themselves as they play

Irina18 [472]

the correct answer is D: all of these

8 0

3 years ago

You move a 2.5 kg book from a shelf that is 1.2 m above the ground to a shelf that is 2.6 m above the ground. What is the change

Sophie [7]

The change in potential energy of an object is given by
$U=mg \Delta h$
where
m is the mass of the object
g is the gravitational acceleration
$\delta h$ is the increase in altitude of the object

In our problem, $m=2.5 kg$ is the mass of the book, $g=9.81 m/s^2$ and
$\Delta h=2.6 m -1.2 m=1.4 m$ is the increase in altitude of the book, so its variation of potential energy is
$U=mg\Delta h=(2.5 kg)(9.81 m/s^2)(1.4 m)=34.3 J$

8 0

4 years ago

An unknown element is found to have two naturally occurring isotopes, 200X and 210X with atomic masses of 200.028 and 210.039 re

Kruka [31]

Answer:

The average atomic mass of X is 206.0346

Explanation:

Atomic mass of 200X = 200.028

% abundance of 200X = 40% = 40/100 = 0.4

Atomic mass of 210X = 210.039

% abundance of 210X = 100% - 40% = 60% = 60/100 = 0.6

Average atomic mass of X = (0.4×200.028) + (0.6×210.039) = 80.0112 + 126.0234 = 206.0346

5 0

4 years ago

Use the table to answer the question.

e-lub [12.9K]

Answer:

The student which is correct is Anya

Explanation:

The wavelength of a wave is the length of one complete wave cycle and it is represented by Greek letter lambda (λ)

The frequency of a wave is the number of waves (complete wave cycles) passing a given point over a given time period and the frequency is represented by the Greek letter nu (ν) and also as "f" (which is the first letter of the word "frequency")

Therefore, the speed, "v", (different from nu (ν)) of the wave is given as follows;

v = f × λ

From which we have;

λ = v/f

∴ λ ∝ 1/f

Which indicates an inversely proportional relationship between the wavelength and the frequenct

From which we have that as the wavelength decreases, the frequency increases

Therefore, Anya decrease increase is correct

4 0

3 years ago