Radon has a half-life of 56s. After what time will it's activity be reduced to (a) 90% (b) 50% (c) 10% of it's initial value​

Answers

Answer 1

Answer:

A) 11.2 s

B) is 56 s

C) 170.8 s


Related Questions

A man on the Moon observes two spaceships coming toward him from opposite directions at speeds of 0.600c and 0.600c. What is the relative speed of the two ships as measured by a passenger on either one of the spaceships

Answers

Answer:

If we use the equation for the transformation of velocities for moving frames:

v' = (v - u) / (1 - u * v / c^2) where we measure the speed of v' approaching from the left where v is in a frame moving at -u towards v'

v' = (.6 c - (-.6 c)) / (1 - (-.6 c) * .6 c / c^2) = 1.2 c / (1 + .6 * .6)

or v' = 1.2 c / (1 + .36) = .88 c

v is approaching from the left at .6 c in the reference frame and the other frame approaches from the right at -.6 c with speed u  (-.6 c) and we measure the speed of v as seen in the frame moving to the left

24. A anvil with a mass of 60 kg falls from a height of 9.5 m. How fast is it going right
before it hits the ground?

V= I*R

V = voltage (measured in volts) V

I = current (measured in amperes) A

R = resistance (measured in Ohms) Ω

Answers

So they give us this

V=IR

V= 1.8

I=0.4

R=?

So we insert the thing that we know.

1.8=0.4*R

We need to leave our unknown value alone. So if our value of 0.4 is multiplying the unknown value it passes to the other side dividing.

So we have this.

Lastly we solve.

R=4.5ohms

The formula to find R is V=IR

V/I=R

So the resistance will be the Voltage divided by the Current

WILL GIVE BRAINLIEST

Answers

Answer:

[tex]2\:\mathrm{m/s^2}[/tex]

From Newton's 2nd Law, we have [tex]\Sigma F=ma[/tex]. Substituting given values, we have:

[tex]40=20a,\\a=\frac{40}{20}=\boxed{2\:\mathrm{m/s^2}}[/tex]

what is the transfer of heat energy by direct contact. A . convection b. radiation c. thermal or heat and d. conduction ​

Answers

Answer:

d. conduction ​

Explanation:

Conduction involves the transfer of electric charge or thermal energy due to the movement of particles. When the conduction relates to electric charge, it is known as electrical conduction while when it relates to thermal energy, it is known as heat conduction.

In the process of heat conduction, thermal energy is usually transferred from fast moving particles to slow moving particles during the collision of these particles. Also, thermal energy is typically transferred between objects that has different degrees of temperature and materials (particles) that are directly in contact with each other but differ in their ability to accept or give up electrons.

Any material or object that allow the conduction (transfer) of electric charge or thermal energy is generally referred to as a conductor. Conductors include metal, steel, aluminum, copper, frying pan, pot, spoon etc.

In conclusion, conduction typically involves the transfer of heat energy by direct contact between two or more conductors such as a pot and electric cooker.

Answer:

d. conduction ​

Explanation:

Conduction is the transfer of energy from one molecule to another by direct contact.

A negative correlation coefficient, such as -.89, means

A. There is no relationship between two variables.

B. As one variable tends to increase or become larger, the other decreases or becomes smaller.

C. There is a direct relationship. As one variable increases, the other also increases or becomes larger.

D. Nothing, a mistake has been made.

Answers

Answer:

B - As one variable increases the other decreases. (-1 to +1)     coefficient

What can be the maximum value of the original kinetic energy of disk AA so as not to exceed the maximum allowed value of the thermal energy

Answers

The question is incomplete. The complete question is :

In your job as a mechanical engineer you are designing a flywheel and clutch-plate system. Disk A is made of a lighter material than disk B, and the moment of inertia of disk A about the shaft is one-third that of disk B. The moment of inertia of the shaft is negligible. With the clutch disconnected, A is brought up to an angular speed ?0; B is initially at rest. The accelerating torque is then removed from A, and A is coupled to B. (Ignore bearing friction.) The design specifications allow for a maximum of 2300 J of thermal energy to be developed when the connection is made. What can be the maximum value of the original kinetic energy of disk A so as not to exceed the maximum allowed value of the thermal energy?

Solution :

Let M.I. of disk A = [tex]$I_0$[/tex]

So, M.I. of disk B =  [tex]$3I_0$[/tex]

Angular velocity of A = [tex]$\omega_0$[/tex]

So the kinetic energy of the disk A = [tex]$\frac{1}{2}I_0\omega^2$[/tex]

After coupling, the angular velocity of both the disks will be equal to ω.

Angular momentum will be conserved.

So,

[tex]$I_0\omega_0 = I_0 \omega + 3I_0 \omega$[/tex]

[tex]$I_0\omega_0 = 4I_0 \omega$[/tex]

[tex]$\omega = \frac{\omega_0}{4}$[/tex]

Now,

[tex]$K.E. = \frac{1}{2}I_0\omega^2+ \frac{1}{2}3I_0\omega^2$[/tex]

[tex]$K.E. = \frac{1}{2}I_0\frac{\omega_0^2}{16}+ \frac{1}{2}3I_0\frac{\omega_0^2}{16}$[/tex]

[tex]$K.E. = \frac{1}{2}I_0\omega_0^2 \left(\frac{1}{16}+\frac{3}{16}\right)$[/tex]

[tex]$K.E. = \frac{1}{2}I_0\omega_0^2\times \frac{1}{4}$[/tex]

[tex]$\Delta K = \frac{1}{2}I_0\omega_0^2 - \frac{1}{2}I_0\omega_0^2 \times \frac{1}{4} $[/tex]

[tex]$2300=\frac{3}{4}\left(\frac{1}{2}I_0\omega_0^2\right)$[/tex]

[tex]$\frac{1}{2}I_0\omega_0^2=2300 \times \frac{4}{3 } \ J $[/tex]

Therefore, the maximum initial K.E. = 3066.67 J

which statement describes the molecules and a reaction once it reaches equilibrium
A. They maintain stable concentrations
B. They stop moving
C. They consist mainly of reactant molecules
D. They react only if they are disturbed

Answers

Answer:

They maintain stable concentrations

Explanation:

Just took the test.

The statement describes the molecules and a reaction once it reaches equilibrium: they maintain stable concentrations, which is option A as the When a chemical reaction reaches equilibrium, the rate of the forward reaction is equal to the rate of the reverse reaction.

What is equilibrium?

Equilibrium is a dynamic state, meaning that the reaction is still ongoing but the rates of the forward and reverse reactions are equal. This means that molecules are still reacting with each other, but at a constant rate, so that the concentrations of the reactants and products remain stable. When a reaction is not at equilibrium, the concentrations of the reactants and products change as the reaction progresses. However, once equilibrium is reached, the concentrations of the reactants and products no longer change, but the individual molecules are still moving and reacting with each other.

Hence, The statement describes the molecules and a reaction once it reaches equilibrium: they maintain stable concentrations, which is an option. A 

Learn more about equilibrium here.

https://brainly.com/question/19324885

#SPJ5

Which of the following. Chemical represent the law of conservation of Matter?

Answers

Answer:

The answer is first one 1...

A 35.0 g bullet strikes a 5.3 kg stationary wooden block and embeds itself in the block. The block and bullet fly off together at 7.1 m/s. What was the original speed of the bullet? (WILL GIVE BRAINLIEST)​

Answers

Answer:

= 1200m/s or 1.2 x [tex]10^{3}[/tex] m/s

Explanation:

What is meant by electricity and magnetism

Answers

Electricity is just the flow of electrons or charges from a point of production through a conductor, to another point where it can be utilized or converted to another form of energy.

Magnetism is the force exerted by magnets when they attract or repel each other. Magnetism is caused by the motion of electric charges from two or more magnetic substances.

Answer:

By Electricity.. We mean the Flow of electrical power or Charge.

While Magnetism is a phenomenon that occurs from or by the Motion of Charges

If a coworker repeatedly asks you out for a date even though she knows you are not interested, what is she guilty of?
A. discrimination
OB. hate speech
OC. psychological harassment
O D. sexual harassment

Answers

D sexual harassment
She would be guilty of sexual harassment.

Water has a heat capacity of 4.184 J/g °C. If 50 g of water has a temperature of 30°C and a piece of hot copper is added to the water causing the temperature to increase to 70°C. What is the amount of heat absorbed by the water?​

Answers

Answer:

Q = 8368 Joules.

Explanation:

Given the following data;

Mass = 50 g

Initial temperature = 30°C

Final temperature = 70°C

Specific heat capacity = 4.184 J/g °C

To find the amount of heat absorbed by the water;

Heat capacity is given by the formula;

[tex] Q = mcdt[/tex]

Where;

Q represents the heat capacity or quantity of heat.

m represents the mass of an object.

c represents the specific heat capacity of water.

dt represents the change in temperature.

dt = T2 - T1

dt = 70 - 30

dt = 40°C

Substituting the values into the equation, we have;

[tex] Q = 50*4.184*40[/tex]

Q = 8368 Joules.

A. Obtain the following: microwave, ruler, something meltable (e.g. candy bar, marshmallows) B. A microwave works by setting up a standing electromagnetic wave inside of a box made of conducting materials. What is the value of an electric field inside a conductor

Answers

Answer:

E = 124.7 N / C

Explanation:

Let's analyze the exercise: the microwave creates an electromagnetic wave of frequency F = 2.45 GHz, this wave is introduced into the microwave cavity and is reflected on the metal walls, which is why one or more standing waves are formed.

The electric field of the standing wave is

            I = E²

            E =√I

where I is the intensity of the radiation.

What is it

             I = P / A

where P is the effective emission power, almost all the power of the microwave and A is the area of ​​the cavity, in the most used microwaves

P = 700 W and the area is A = 25 x 18 cm² = 0.045 m²

             I = 700 / 0.045

             I = 15555.56 W/m²

let's calculate the electric field

            E = √15555.56

            E = 124.7 N / C

Are surface currents warm or cold?
A:war m
B:cold

Answers

Answer:

Cold

Explanation:

Im pretty sure im sorry if I am wrong

cold is the answer :))

I NEED HELP THIS QUESTION IS SO HARDDD!!

Answers

Answer:

c

Explanation:

search it up

Answer:

Option A.

Explanation:

Because this is a lunar eclipse it normally happens 2 times a year.  This is a decently rare phenomenon due to the positions they have to be in to make a lunar eclipse.  Therefore, it is option A.

Using a 2.5 meter long lever, we want to lift a body weighing 15 kilograms. If the lever support so that the pitch of the load is 55 cm, determine the force we must apply to be lift that burden? HURRYYYYY PLEASE ITS A TEST​

Answers

Answer:

F = 668.9N

Explanation:

Using the formula;

m1d1 = m2d2

m1 and m2 are the masses

d1 and d2 are the distances

Substitute;

15 * 2.5 = x * (55/100) [55cm was converted to metres]

37.5 = 0.55x

Swap

0.55x = 37.5

x = 37.5/0.55

x = 68.18kg

Since F = mg

F = 68.18 * 9.81

F = 668.9N

This gives the required force

Mass, volume and density are all properties of

Answers

Answer:

Properties of matter

Explanation:

All properties of matter are either extensive or intensive and either physical or chemical. Extensive properties, such as mass and volume, depend on the amount of matter that is being measured. Intensive properties, such as density and color, do not depend on the amount of matter.

Answer:

The pythagoream theorem

Explanation:

A sound wave with a frequency of 700 Hz and a wavelength of 5 m travels through a liquid. How fast does sound travel through the liquid?

A.
140 m/s
B.
0.007 m/s
C.
3500 mHz
D.
3500 m/s

Answers

Answer:

It’s D, 3500 m/s
It’s D 3500 m/s in most cases

With what tension must a rope with length 2.90 m and mass 0.125 kg be stretched for transverse waves of frequency 42.0 Hz to have a wavelength of 0.740 m

Answers

Answer:

41.64 N

Explanation:

Applying,

v = √(T/m')................ Equation 1

Where v = velocity of the wave, T = Tension of the rope, m' = mass per unit length of the rope.

make T the subject of the equation,

T = v²m'................. Equation 2

But,

v = λf............... Equation 3

Where λ = wavelength, f = frequency

And

m' = m/L........... Equation 4

Where m = mass of the rope, L = length of the rope

Substitute equation 3 and equation 4 into equation 2

T = (λf)²(m/L).............. Equation 5

From the question,

Given: λ = 0.740 m, f = 42 Hz, m = 0.125 kg, L = 2.9 m

Substitute these values into equation 5

T = (42×0.74)²(0.125/2.9)

T = 41.64 N

Convex lenses cause light rays to _____.

Answers

Answer:

to meet at a single point

(causing rays of light that are initially parallel to meet at a single point)

hope this helps:)

Explanation:

Answer:

focus

Explanation:

see more here

https://youtu.be/CJ6aB5ULqa0

If an electromagnetic wave has a frequency of 6×10^5 hz, what is its wavelength? ​ what is its wavelength? A. 2 x 10^12m, B. 5 x 10^14m, C. 5 x 10^2m, 2 x 10^-3m

Answers

Answer:

5*10^2

Explanation:

A p e x

g Monochromatic light with wavelength 633 nn passes through a narrow slit and a patternappears on a screen 6.0 m away. The distance on the screen between the centers of thefirst minima on either side of the screen is 32 mm. How wide (in mm) is the slit

Answers

Answer:

d = 1.19 x 10⁻⁴ m = 0.119 mm

Explanation:

This problem can be solved by using Young's double-slit experiment formula:

[tex]Y = \frac{\lambda L}{d}[/tex]

where,

Y = fringe spacing = 32 mm = 0.032 m

L = slit to screen distance = 6 m

λ = wavelength of light = 633 nm = 6.33 x 10⁻⁷ m

d = slit width = ?

Therefore,

[tex]0.032\ m = \frac{(6.33\ x\ 10^{-7}\ m)(6\ m)}{d}\\\\d = \frac{(6.33\ x\ 10^{-7}\ m)(6\ m)}{0.032\ m}[/tex]

d = 1.19 x 10⁻⁴ m = 0.119 mm

In the experiment, a meter is hooked up to a speaker to monitor the amplitude of the received sound. Suppose the background signal level is 13 mV, the signal is 91 mV with no attenuator and is 25 mV with an attenuator in place. Calculate pt/pi including the background correction.

Answers

Answer:

The answer is "[tex]15.38\%[/tex]"

Explanation:

Background[tex]= 13 \ mv\\\\[/tex]

corrected signal[tex]= 91 \ mv-13\ mv= 78\ mv\\\\[/tex]

with attenuator[tex]=25\ mv-13\ mv= 12\ mv\\\\[/tex]

[tex]\to \frac{p_t}{p_i}=\frac{12}{78}\times 100= 15.38\%[/tex]

Henry has 8 pieces of pizza that he wants to give equally to 3 friends how much pizza will each friend get

Answers

Each friend will get 2 slices of pizza.

8 divided by 3= 2.7
8/3 = 2.66666667
2.7

Help me please I don’t understand

Answers

Answer:

a. hydroelectric power plant

source of sinusoidal electromagnetic waves radiates uniformly in all directions. At a distance of 10.0 m from this source, the amplitude of the electric field is measured to be 3.50 N>C. What is the electric-field amplitude 20.0 cm from the source

Answers

Answer:

[tex]175\ \text{N/C}[/tex]

Explanation:

[tex]E_1[/tex] = Initial electric field = 3.5 N/C

[tex]E_2[/tex] = Final electric field

[tex]r_1[/tex] = Initial distance = 10 m

[tex]r_2[/tex] = Final distance = 20 cm

Electric field is given by

[tex]E=\sqrt{\dfrac{2P}{\pi r^2c\varepsilon_0}}[/tex]

So,

[tex]E\propto \dfrac{1}{r}[/tex]

[tex]\dfrac{E_2}{E_1}=\dfrac{r_1}{r_2}\\\Rightarrow E_2=E_1\dfrac{r_1}{r_2}\\\Rightarrow E_2=3.5\dfrac{10}{0.2}\\\Rightarrow E_2=175\ \text{N/C}[/tex]

The electric field amplitude at the required point is [tex]175\ \text{N/C}[/tex].

A closed loop conductor that forms a circle with a radius of 2.0 m is located in a uniform but changing magnetic field. If the maximum emf Induced in the loop is 5.0 V what is the maximum rate at which the magnetic field strength is changing if the magnetic field is oriented perpendicular to the plane in which the loop lies

Answers

Answer:

The maximum rate at which the magnetic field strength is changing if the magnetic field is oriented perpendicular to the plane in which the loop lies 0.398 T/s.

Explanation:

Given;

radius of the circular loop, r = 2.0 m

maximum induced emf, E = 5.0 V

The emf induced in a magnetic field is given as;

[tex]emf = \frac{d\phi}{dt} \\\\\phi = AB\\\\emf = A\frac{dB}{dt} \\\\\frac{dB}{dt} = \frac{emf}{A} \\\\where;\\A \ is \ the \ area \ circular \ l00p = \pi r^2 = \pi (2)^2 = 4\pi \ m^2\\\\\frac{dB}{dt} = \frac{5}{4\pi} \\\\\frac{dB}{dt} = 0.398 \ T/s[/tex]

Therefore, the maximum rate at which the magnetic field strength is changing if the magnetic field is oriented perpendicular to the plane in which the loop lies 0.398 T/s.

A 17-mm-wide diffraction grating has rulings of 530 lines per millimeter. White light is incident normally on the grating. What is the longest wavelength that forms an intensity maximum in the fifth order

Answers

Answer:

377 nm

Explanation:

Number of lines per meter is, [tex]N &=530 \times 1000 \\ &=530000 \text { lines } / \mathrm{m} \end{aligned}[/tex]

Grating element is, [tex]d=\frac{1}{N}[/tex]

[tex]=1.8868 \times 10^{-6} \mathrm{~m}[tex]

Order is, n=5

Condition for maximum intensity is, [tex]d \sin \theta=n \lambda[/tex]

 [tex]\lambda &=\frac{1.8868 \times 10^{-6}}{5(\sin 90)} \\ &=0.377 \times 10^{-6} \mathrm{~m} \\ &=377 \mathrm{~nm}[/tex]

One thing you really notice is the complex, feathery, knotty structure of the gas and dust in our galaxy. If you look around, you can see a couple more objects that might be good candidates for being other galaxies with their own star-forming regions. What are these objects called

Answers

Answer:

Orion Nebula & cone nebula

Explanation:

From the huge, youthful stars that are forming the nebula to the pillars of thick gas that could be the homes of burgeoning stars, the Orion Nebula is a picture book of star formation. The four heaviest stars in the nebula reside in the bright central field. Since the stars are arranged in a trapezoid shape, they are known as the Trapezium.

These stars' ultraviolet radiation is cutting a hole in the nebula and stars that are already young enough to have disks of material encircling them can be seen near the Trapezium stars. Protoplanetary disks, also known as (proplyds) are too small to be seen distinctly and the disks are the foundation of solar systems.

The Cone Nebula is a monstrous creation, which resembles a nightmare beast flaring up from a crimson sea, is simply a benevolent pillar of gas and ashes. The Cone Nebula is so identified because it has a conical appearance in ground-based photographs. This massive pillar is located in a tumultuous star-forming area with gnarled mountainpeak of cold gas and dust is visible.

Problem 3:A starship voyages to a distant planet 10 ly away. The astronauts in the starship reach theplanet and then they immediately return to the Earth at the same speed. The round trip from the Earthto the planet and back to the Earth takes 25 years.(a) What is the speed of the starship

Answers

Answer:

speed = 0.8c

Explanation:

Given :

Distance from earth to the distant planet = 10 ly

Time taken by the astronauts for the entire journey = 25 years

The time taken to reach the planet is [tex]$t_1=\frac{25}{2}$[/tex]

                                                                  = 12.5 years

Therefore, speed of the starship can be calculated by :

[tex]$\text{Speed} = \frac{\text{distance}}{\text{time}}$[/tex]

[tex]$v=\frac{10 \times c \times 3.15 \times 10^7}{12.5 \times 3.15 \times 10^7}$[/tex]

  [tex]$=0.8c$[/tex]

Therefore the speed of the starship is 0.8c

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