a radioactive element has a half-life of 30 days. calculate the mass of the element that remains after 20 days if 100g of the element decays. Also, calculate the decay constant.

Answer:

should be D

Explanation:

pls make this the brainliest

Answer:

Explanation:

There are many laws in physics, that started out as theories and became scientific truths only after an experiment was performed that confirmed that the theory was true.

One of the most famous theories was the guess that the gravitational Force was a constant amount that depended on mass and distance. It was incredibly difficult to prove because the with large masses and small distances, the force is quite small.

Newton proposed the existence of the gravitational force in 1687 and Cavendish found its precise truth in 1798 -- 111 years after Newton said it was so.

Newton proposed a theory. Cavendish proved it to be a law later. Even then, Einstein proposed the modern law.

Answer:

94

Explanation :

Of these 118 elements, 94 occur naturally on Earth. Six of these occur in extreme trace quantities: technetium, atomic number 43; promethium, number 61; astatine, number 85; francium, number 87; neptunium, number 93; and plutonium, number 94.

source: Wikipedia

Answer:

12

Explanation:

A x B = |A||B|sin ©

A x B = 3x4 sin 90

= 12

Answer:

2.6 seconds

Explanation:

You have to divide the distance by the velocity to find the time:

46/18 = 2.55 ≈ 2.6 seconds

The answer you are looking for is approximately 2.6 seconds.

Solution/Explanation:

To get the correct answer, you must divide the distance and velocity.

This means that 46÷18=2.5556.

2.5556≈2.6.

So, therefore, the final answer is approximately 2.6 seconds.

I hope that this has helped you. Enjoy your day, and take care.

Answer:

Explanation:

the aversge is 3.4t

Answer:

i. [tex]u=\frac{2s}{t}-v[/tex]

ii. [tex]v=\frac{2s}{t}-u[/tex]

Explanation:

i.)

[tex]s=\frac{1}{2}(u+v)t\\\\2s=(u+v)t\\\\\frac{2s}{t}=u+v\\\\\frac{2s}{t}-v=u[/tex]

ii.)

[tex]s=\frac{1}{2}(u+v)t\\\\2s=(u+v)t\\\\\frac{2s}{t}=u+v\\\\\frac{2s}{t}-u=v[/tex]

Answer:

the tendency of a body to float or to rise when submerged in a fluid testing an object's buoyancy.

Explanation:

The meaning is from Merriam Webster for more such unique nd it also has easy meanings you can download that

(Source Merriam Webster)

Hope it helps unnie

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Have a nice day

Anything that displaces fluid is acted on by an upward force equal to the weight of the displaced fluid.

Explanation:

Relative density of mercury = 13600 Kgm-3/1000 kg m-3 = 13.6.

this atom has nine electrons

Explanation:

since electrons are found outside the nucleus of an atom and they are negatively charged

Explanation:

The correct answer is option B

Answer:

C. When ice melts, it absorbs energy.

Explanation:

When ice melts, it is getting hotter by absorbing energy and changes from a solid to a liquid. This is an endothermic reaction.

Answer:

A yxiigxih5dd8yixc99uf8g

Answer:

thermal energy is the different forms of energy

Answer:

Ans:

Explanation:

MA=L/E=500N/200N=5/2

VR=ED/LD=60cm/20cm=3

Thus, Efficiency=(Ma*100%)/VR=83.34%

please mark this answer as brainlist

Answer:

A wavefront is the long edge that moves, for example, the crest or the trough. Each point on the wavefront emits a semicircular wave that moves at the propagation speed v.

Answer:

A wavefront is a surface containing points affected in the same way by a wave at a given time such as crest and troughs

Answer:

c

Explanation:

A shift inward of the production possibilities curve signifies that: C. The available production resources have decreased, so potential production levels will decrease.

A production possibilities curve (PPC) is also referred to as production possibilities frontier (PPF) and it can be defined as a curve that illustrates the maximum (best) combinations of two (2) products which can be produce in an economy if they both depend on these two (2) main factors;

Basically, the production possibilities curve (PPC) illustrates the maximum combinations of goods that are available with fixed technology and resources.

Furthermore, an inward shift of the production possibilities curve (PPC) signifies that the available resources used for production have decreased, so potential production levels would also decrease.

Read more: https://brainly.com/question/17053992

Answer:

GALELOI GALELEI:HE WAS A FAMOUS SCIENTIST WHO MADE PENDULAM ALSO HE EXPLAINED THE MOTION AND INERTIA

ISAAC NEWTON:3 LAWS OF MOTION,3 FORMULAS OF MOTION,GRAVITY

Answer:

IV what is it's potential energy at the maximum height

Variables - Initial position, Final position, Distance between Positions, Time.

Instruments - Ruler (Distance between Positions), Chronometer (Time)

Average Velocity is equal to the change in Position divided by Time. Since Incline is a Straight Line, then Position Change and Traveled Distance are the same. In this case, we need to define Initial and Final Position of the marble, and then we have to measure the distance between these Points.

Distance between Initial and Final Position can be measured by a Ruler, whereas Time can be measured by a Chronometer.

In a nutshell, Initial and Final Position and Time are variables needed to be measured. Besides, Distance between Initial and Final Position can be found by means of a Ruler, and Time is found with the help of a Chronometer.

Please see this question related to concept of Average Velocity: https://brainly.com/question/862972

Answer:

[tex]20 + 10 = 30 \\ 30and50 in \: parallel \\ = \frac{50 \times 30}{50 + 30} \\ = \frac{1500}{80} \\ 18.75 \\ 30nd40parallel \\ \frac{30 \times 40}{70} \\ \frac{1200}{70} = 17.143 \\ total = 18.75 + 17.143 = 35.893ohm \\ thank \: u[/tex]

Answer:

[tex]20 + 10 = 30 \\ \\ \frac{50 \times 30}{50 + 30} \\ \\ \frac{1500}{80} \\ \\ = 18.45 \\ \\ = second \: \\ \\ \frac{30 \times 70}{70} \\ \\ \frac{1200}{70} \\ \\ = 17.143 \\ \\ total = 18.45 + 17.143 \\ \\ = 35.830hm[/tex]

Using newtons law

[tex]\\ \rm\longmapsto F=ma[/tex]

[tex]\\ \rm\longmapsto m=\dfrac{F}{a}[/tex]

[tex]\\ \rm\longmapsto m=\dfrac{700}{9.8}[/tex]

[tex]\\ \rm\longmapsto m=71.4kg[/tex]

Relative motion means a motion relative to a reference point. We can also say, relative motion means motion referred or observed from a reference point.

For example, Alex is in a train and Ace is at the station, when the train starts moving, for Ace it is moving at a speed of 10 m/s, but for Alex it is moving at 0 m/s, or we can say that it is at rest for Alex, but in motion for Ace. This is relative motion.

Answer:

relative motion is the motion of an object compared to that of another object.for example two cars driving in the same highway in the same direction.

I hope this helps

Answer:

It only took me an hour

Explanation:

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3. The xylem and phloem arranged side by side on same radius is called

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4. Which is formed during anaerobic respiration

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Answer:

Fundamental units are all those units which are independent of any other unit (including themselves). Derived units are all those units which are obtained by multiplying and/or dividing one or more fundamental units with or without introducing any other numerical factor.

Here are some basic SI units .

Answer:

The north part of the compass needle is attracted to the magnetic south pole of Earth, which is also known as the geographical north pole.  When it comes to magnets, opposites attract. This fact means that the north end of a magnet in a compass is attracted to the south magnetic pole, which lies close to the geographic north pole. Magnetic field lines outside of a permanent magnet always run from the north magnetic pole to the south magnetic pole. Therefore, the magnetic field lines of the earth run from the southern geographic hemisphere towards the northern geographic hemisphere.

Explanation: