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3 years ago

Why echo sound cannot be heard in small room

1 answer:

7 0

They can't hear an echo in small room because in it the sound can't be reflected back. For an echo of a sound to be heard,the minimum distance between the source of sound and the walls of the roomshould be 17.2 m. Obviously,in asmall room echoes cannot beheard.

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a man of mass 50 kg on the top floor of skyscraper step into an elevator what is the max weight as the elevator moves downward

shtirl [24]

514.5 N is the answer

6 0

3 years ago

Alex swims at an average speed of 45m/min. how far does he swim in 1 min 24 sec?

saveliy_v [14]

Answer:

63 m

Explanation:

Average speed of swimming = 45 m/min

Time = 1 minute 24 seconds

Converting time into minutes:

Formula:

Putting values, we get.

Thus, Alex swims for 63 m in 1 minute and 24 seconds.

6 0

3 years ago

Which option lists a form of potential energy followed by a form of kinetic energy?

Nadusha1986 [10]

Answer:

Magnetic energy and electromagnetic energy form of potential energy followed by a form of kinetic energy.

(B) is correct option.

Explanation:

Given that,

Lists a form of potential energy followed by a form of kinetic energy

We know that,

Sound energy :

The movement of energy through object it is called sound energy. When a object produced vibration by force then it moves in wave.

Sound wave is example of kinetic energy.

Nuclear energy :

The store energy in the nucleus of the atom it is called nuclear energy. This energy released when occurs fusion and fission.

Nuclear energy is the example of potential energy

Magnetic energy :

Magnetic energy is a type of potential energy which is depend on distance and position in the magnetic field.

Electromagnetic energy :

Electromagnetic energy is light energy. it is type of kinetic energy.

Gravitational energy :

Gravitational energy is a type of potential energy. It is an energy related with gravity or gravitational force.

Elastic energy :

The store energy in elastic object it is called elastic energy. This energy is a type of potential energy.

Electrical energy :

The movement of electrons is called electrical energy. When electrons move through a wire then it is are called electricity. Electrical energy is type of kinetic energy.

Hence, Magnetic energy and electromagnetic energy form of potential energy followed by a form of kinetic energy.

(B) is correct option.

4 0

3 years ago

Read 2 more answers

4. How does a molecule differ from an atom

tia_tia [17]

Answer:

Explanation:

In a molecule, atoms are bonded together by single, double, or triple bonds. An atom has a nucleus surrounded by electrons. ... So another difference between atoms and molecules is that when similar atoms combine together in varying numbers, molecules of different properties can be formed.

8 0

3 years ago

Read 2 more answers

The half-life of Iodine-131 is 8.0252 days. If 14.2 grams of I-131 is released in Japan and takes 31.8 days to travel across the

MakcuM [25]

Answer:

Explanation:

Half-life problems are modeled as exponential equations. The half-life formula is $P=P_o\left (\dfrac{1}{2} \right)^{\frac{t}{k}}$ where $P_o$ is the initial amount, $k$ is the length of the half-life, $t$ is the amount of time that has elapsed since the initial measurement was taken, and $P$ is the amount that remains at time $t$ .

$P=14.2\left (\dfrac{1}{2} \right)^{\frac{t}{8.0252}}$

<u>Deriving the half-life formula</u>

If one forgets the half-life formula, one can derive an equivalent equation by recalling the basic an exponential equation, $y=a b^{t}$ , where $t$ is still the amount of time, and $y$ is the amount remaining at time $t$ . The constants a and b can be solved for as follows:

Knowing that amount initially is 14.2g, we let this be time zero:

$y=a b^{t}$

$(14.2)=ab^{(0)}$

$14.2=a *1$

$14.2=a$

So, $a=14.2$ , which represents out initial amount of the substance, and our equation becomes: $y=14.2 b^{t}$

Knowing that the "half-life" is 8.0252 days (note that the unit here is "days", so times for all future uses of this equation must be in "days"), we know that the amount remaining after that time will be one-half of what we started with:

$\left(\frac{1}{2} *14.2 \right)=14.2 b^{(8.0252)}$

$\dfrac{7.1}{14.2}=\dfrac{14.2 b^{8.0252}}{14.2}$

$0.5=b^{8.0252}$

$\sqrt[8.0252]{\frac{1}{2}}=\sqrt[8.0252]{b^{8.0252}}$

$\sqrt[8.0252]{\frac{1}{2}}=b$

Recalling exponent properties, one could find that $\left ( \frac{1}{2} \right )^{\frac{1}{8.0252}}=b$ , which will give the equation identical to the half-life formula. However, recalling this trivia about exponent properties is not necessary to solve this problem. One can just evaluate the radical in a calculator:

$b=0.9172535661...$

Using this decimal approximation has advantages (don't have to remember the half-life formula & don't have to remember as many exponent properties), but one minor disadvantage (need to keep more decimal places to reduce rounding error).

So, our general equation derived from the basic exponential function is:

$y=14.2* (0.9172535661)^t$ or $y=14.2*(0.5)^{\frac{t}{8.0252}}$ where y represents the amount remaining at time t.