Find the radioactivity of a 1 g sample of 226Ra given that [tex]t_{1/2}=1620[/tex] years and Avogadro's number = 6.023 × [tex]10^{23}[/tex].

Answer:

[tex]\displaystyle \rho=1.25\ g/ml[/tex]

Explanation:

Density

The density of a substance is the mass per unit volume. The density varies with temperature and pressure.

The formula to calculate the density of a substance of mass (m) and volume (V) is:

[tex]\displaystyle \rho=\frac{m}{V}[/tex]

The cube has a mass of m=3.75 g and a volume of V=3 ml, thus the density is:

[tex]\displaystyle \rho=\frac{3.75\ g}{3\ ml}[/tex]

[tex]\boxed{\displaystyle \rho=1.25\ g/ml}[/tex]

Since 1 kg=1000 mg and 1 lt = 1000 ml, the density has the same value but with different units:

[tex]\displaystyle \rho=1.25\ kg/l[/tex]

Answer:

a. 3.45 kHz b. 5 cm c. 7.5 cm

Explanation:

a. What is the frequency of the tuning fork?

For a tube open at both ends, the frequency, f = nv/2L. The smallest frequency at the smallest length of air column, L = 5 cm = 0.05 m is the fundamental frequency and there, n = 1 and v = speed of sound in air = 345 m/s.

So, f = v/2L

So, f = 345 m/s/(2 × 0.05 m)

= 345 m/s ÷ 0.1 m

= 3450 Hz

= 3.45 kHz

b. What is the value of L for the second resonant position?

The second resonant frequency is f' = 2f

= 2 × 3450 Hz

= 6900 Hz

Since f = nv/2L and f' = second resonant frequency when n = 2.

So, f' = 2v/2L

f' = v/L

L = v/f'

= 345 m/s ÷ 6900 Hz

= 0.05 m

= 5 cm

c. What is the value of L for the third resonant position?

The third resonant frequency is f" = 3f

= 3 × 3450 Hz

= 10350 Hz

Since f = nv/2L and f" = third resonant frequency when n = 3.

So, f" = 3v/2L

2f' = 3v/L

L = 3v/2f'

= 3 × 345 m/s ÷ (2 × 6900 Hz)

= 1035 m/s ÷ 13800 Hz

= 0.075 m

= 7.5 cm

a)The frequency of the tuning fork will be 3.45 kHz.

b) The value of L for the second resonant position will be 5 cm.

c) The value of L for the third resonant position will be 7.5 cm.

Frequency is defined as the number of repetitions of a wave occurring waves in 1 second.

The tuning fork's frequency for a tube with both ends open is;

f = nv/2L

f = 345 m/s/(2 × 0.05 m)

f= (345 m/s) / (0.1 m)

f= 3450 Hz

f= 3.45 kHz

f' = 2f is the second resonant frequency.

f'= 2 × 3450 Hz

f'= 6900 Hz

f = nv/2L

For n=2,

f' = 2v/2L

f' = v/L

The value of L for the second resonant position;

L = v/f'

L= 345 m/s ÷ 6900 Hz

L= 0.05 m

L= 5 cm

f' = 3f is the third resonant frequency.

f' = 3 × 3450 Hz

f'= 10350 Hz

f = nv/2L

For, n = 3.

f' = 3v/2L

2f' = 3v/L

The value of L for the third resonant position;

L = 3v/2f'

L=( 3 × 345 m/s)/(2 × 6900 Hz)

L= 1035 m/s / 13800 Hz

L= 0.075 m

L= 7.5 cm

Hence,The frequency of the tuning fork,value of L for the second resonant position and value of L for the third resonant position will be 3.45 kHz. 5 cm and 7.5 cm respectively.

To learn more about the frequency refer to the link;

https://brainly.com/question/14926605

#SPJ5

Answer:

Impulse = 0.9408Ns

Explanation:

Impulse is the product of force and time

Impulse = Ft

Given

Force F = mg

F = 12(9.8)

F = 117.6N

Time = 8 * 10^-3 = 0.008s

Get the impulse

Impulse = 117.6*0.008

Impulse = 0.9408Ns

Answer:

v = 21.52 m/s

Explanation:

Given that,

The distance covered by the car, d = 6200 km

Time taken by the car, t = 80 hours

We need to find the speed of the car. The speed of an object is given by total distance dividing total time.

[tex]v=\dfrac{6200\times 10^3\ m}{80\times 3600}\\\\v=21.52\ m/s[/tex]

So, the speed of the car is 21.52 m/s.

Answer:

t = Δa / v

Explanation:

To know which option is not true, we shall fine a relationship between acceleration (a), velocity (v), time (t) and radius (r). This is illustrated below:

Acceleration can simply be defined as the rate of change of velocity with time. Mathematically, it is expressed as shown below:

Acceleration = change in velocity / time

a = Δv / t ..... (1)

But

Δv = v₂ – v₁

Substitute the value of Δv into equation (1)

a = Δv / t

a = v₂ – v₁ / t ....... (2)

From equation (1), make Δv the subject of the equation.

a = Δv / t

Cross multiply

Δv = at .... (3)

From equation (1), make t the subject of the equation.

a = Δv / t

Cross multiply

at = Δv

Divide both side by a

t = Δv /a ...... (4)

From circular motion, centripetal's force is given by:

F = mv²/r

F = ma꜀

Therefore,

ma꜀ = mv²/r

Cancel out m

a꜀ = v²/r

SUMMARY:

a = Δv / t

a = v₂ – v₁ / t

Δv = at

t = Δv /a

a꜀ = v²/r

Considering the options given in question above, t = Δa / v is not a true statement.

Answer:

Option 4

Explanation:

Answer:

D: 0.239

Explanation:

Equation for ideal efficiency is;

η = 1 - (T_c/T_h)

We are told that;

steam comes out at 112° C. Thus, T_h = 112°C. Converting to Kelvin gives; T_h = 112 + 273 = 385 K

The one exiting into the condenser is kept at 20°C. Thus; T_c = 20 + 273 = 293 K

Thus;

η = 1 - (293/385)

η = 0.239

Answer:

due to the land structure of Nepal

Answer:

a mistake

Explanation:

Answer: A controlled experiment is a scientific test done under controlled conditions, meaning that just one (or a few) factors are changed at a time, while all others are kept constant. In some cases, there is no good way to test a hypothesis using a controlled experiment  I hope this helps you

Explanation:

Explanation:

Elastic string constant (k)

= Slope of the graph F/x

= 15.0N/10.0m = 1.50N/m

Hence,

EPE = 0.5kx² = 0.5(1.50N/m)(3.0m)² = 6.75J.

Answer:

6.8

Explanation:

Answer: Taxpayers

Explanation:

Taking alcohol before driving or while driving is dangerous and has resulted in lots of accidents and deaths. Alcohol tampers with the normal functioning of the brain, and also impairs ones reasoning.

Alcohol impaired driving cases handled by government officials are paid for by the taxpayers. A tax is the levy that the people in the country pays. Those funds are used in handling different government objectives and this is one of such ways.

Answer:

letter B.

Explanation:

Answer: A

0.1

Explanation: I did this

Answer:

196

Explanation:

subtract 24 from 220 to get your answer.

Answer:

100 beats for minute

Explanation:

Adults ( age 18 and over) 60 - 100 beats per minute

Answer:

The answer is radio waves

Answer:

no, not all three contains iron

no, not all three also contain magnets

Explanation:

a has the magnet

b and c have pieces of iron

Answer:

Line emission.

Explanation:

According to Isaac Newton, he postulated that light consists of little (tiny) particles which typically travels in a straight line and from his experimental investigation he observed that white light comprises of a mixture of colors.

Sir Newton observed that, when light shines on a piece of metal, the metal releases electrons because the energy of the tiny light particles are greater than the binding energy of the electrons residing in the metal. This theory is known as the particle model of light.

A line emission would appear in a spectrum when specific wavelength is being emitted by the source of light.

When a high voltage is applied to a low-pressure gas causing it to glow, it will generate line emission.

For example, if a sample of hydrogen gas at low-pressure undergoes or experiences a high voltage electrical discharge, the isolated hydrogen gas would generate a red light (line emission).

Answer:

It contains approximately 14,568.7 square meters

Explanation:

Area Units Conversion

There are several units to express the area of a shape:

[tex]cm^2,\ m^2,\ km^2,\ ft^2,\ in^2,\ acres, \ hectares[/tex]

The process of expressing the area from one unit to the other is called a conversion.

Specifically, we are interested in converting from acres to square meters. The rule to make the conversion is:

[tex]1 acre = 4,046.86\ m^2[/tex]

The plot of land has 3.6 acres, thus its area is:

[tex]3.6 * 4046.86 =14,568.696\ m^2[/tex]

It contains approximately 14,568.7 square meters

Answer:

25 cm

Explanation:

Given that :

Displacement, x = 50 cm

In a spring, the force is given thus ;

F = kx ; where, F = Force, k = spring constant

Hence,

F = 50k - - - (1)

If two identical springs are attached to the mass ;

Fnet = F1 + F2

Fnet = F = kx' + kx'

x' = Displacement

Spring constant k and x' will be the same in the two springs ;

Hence,

F = 2kx' - - - (2)

Equating (1) and (2)

F = F

50k = 2kx'

50 = 2x'

x' = 50 / 2

x' = 25

Hence, the spring will stretch by 25cm

Answer:

25m

Explanation:

Answer:

Answer is explained in the explanation section below.

Explanation:

It can be determined by the use of Fourier's law of heat conduction.

Fourier's Law of Heat Conduction: States that, the rate of heat transfer is directly proportional to the temperature change from higher temperature to lower temperature. And it is directly proportional to the area perpendicular to the direction of the heat flow.

Through this statement, we can write the equation of the Fourier's law:

Q = Rate of Heat transfer.

A = Area

dT = Change in Temperature from Higher to Lower = T1 - T2, where T1 is assumed to be higher temperature.

dx = thickness of the wall, through which heat is transferring.

So,

Q is directly proportional to Area perpendicular to the direction of the heat flow.

So, we can write:

Q [tex]\alpha[/tex] A

And

Q is directly proportional to temperature change.

So, we can write

Q [tex]\alpha[/tex] dT/dx

So, in order to remove the proportionality sign, we need to introduce a constant, which is ( -K) here, Thermal conductivity material of the plane wall.

So,

Q  = - K.A . dT/dx

or

Q = - K . (H.W) . (T1-T2)/L

where, H = height of the wall

W = width of the wall

L = length of the wall.

So, by using the above equation, we can definitely determine the rate of heat transfer through a plane -wall.

Note: for your ease, I have drawn a schematic of the plane-wall and attached in the attachment.

Answer:

The force required is 3,104 N

Explanation:

Force

According to the second Newton's law, the net force exerted by an external agent on an object of mass m is:

F = ma

Where a is the acceleration of the object.

On the other hand, the equations of the Kinematics describe the motion of the object by the equation:

[tex]v_f=v_o+at[/tex]

Where:

vf is the final speed

vo is the initial speed

a is the acceleration

t is the time

Solving for a:

[tex]\displaystyle a=\frac{v_f-v_o}{t}[/tex]

We are given the initial speed as vo=20.4 m/s, the final speed as vf=0 (at rest), and the time taken to stop the car as t=7.4 s. The acceleration is:

[tex]\displaystyle a=\frac{0-20.4}{7.4}[/tex]

[tex]a=-2.757\ m/s^2[/tex]

The acceleration is negative because the car is braking (losing speed). Now compute the force exerted on the car of mass m=1,126 kg:

[tex]F = 1,126\ kg * 2.757\ m/s^2[/tex]

F= 3,104 N

The force required is 3,104 N

Answer:

the relationship is scalar, it is independent of the specific reference system

The statement is false

Explanation:

When the concepts of work and energy are being used, a reference system must be defined to perform the calculations,

in the case of work it is defined by the relation

          W = F. d

where the point represents the scalar product, therefore the work is a scalar magnitude, it has only modulus for which any reference system is selected since the result is independent of the direction of the force, only the projection of the force depends in the given direction.

For the part of the energy it therefore has two main forms, kinetic energy and potential energy.

For kinetic energy the expression is

         K = ½ m v²

therefore, the energizes only depends on the speed module and any reference system, since it will be selected

for gravitational and elastic power energy. It does not depend on the specific value at the point but on the difference with respect to an arbitrarily defined zero, therefore, as the difference is constant, it is independent of the reference system used.

In conclusion, since the relationship is scalar, it is independent of the specific reference system, so we can select several reference systems

Answer:

Answer: (A) 0.75 m/s^2

Explanation:

The Second Newton's law states that an object acquires acceleration when an external unbalanced net force is applied to it.

That acceleration is proportional to the net force and inversely proportional to the mass of the object.

It can be expressed with the formula:

[tex]\displaystyle a=\frac{F_n}{m}[/tex]

Where

Fn = Net force

m  = mass

The ice skater pushes against a wall with a force of 59 N. The wall returns the force and the skater now has a net force of Fn=59 N that makes him accelerate. Being m=79 kg the mass of the skater, the acceleration is:

[tex]\displaystyle a=\frac{59}{79}[/tex]

[tex]a = 0.75\ m/s^2[/tex]

Answer: (A) 0.75 m/s^2

Answer:

The frequency of this wave is [tex]3\; \rm Hz[/tex].

Explanation:

The frequency [tex]f[/tex] of a wave is the number of wavelengths that this wave covers in unit time (typically a second.)

The wave in this question travels at [tex]v = 15\; \rm m \cdot s^{-1}[/tex]. In other words, this wave covers [tex]15\; \rm m[/tex] in unit time (a second.) How many wavelengths [tex]\lambda[/tex] would that [tex]15\; \rm m\;[/tex] correspond to?

The question states that the wavelength of this wave is [tex]\lambda = 5\; \rm m[/tex]. Therefore, there would be [tex]15 / 5 = 3[/tex] wavelengths in the [tex]15\; \rm m[/tex] span that this wave covered in the unit time of one second ([tex]1\; \rm s[/tex].) Hence, the frequency of this wave would be [tex]3\; \rm s^{-1}[/tex] (three per second,) which is equivalent to [tex]3\; \rm Hz[/tex] (three Hertzs.)

In general, the frequency [tex]f[/tex] of a wave with speed [tex]v[/tex] and wavelength [tex]\lambda[/tex] would be:

[tex]\displaystyle f = \frac{v}{\lambda}[/tex].

For the wave in this question:

[tex]\begin{aligned}f &= \frac{v}{\lambda} \\ &= \frac{15\; \rm m \cdot s^{-1}}{3\; \rm s} = 3\; \rm s^{-1} = 3\; \rm Hz\end{aligned}[/tex].

Answer: 200 joules I think.

Explanation:

Answer:

The pressure at Mombasa is 101.396 KPascal.

Explanation:

Given: Reading on barometer = 760 mm

                                                  = 0.76 m

           Density of mercury = 1.36 x [tex]10^{4}[/tex] kg/[tex]m^{3}[/tex]

In this case, the pressure can be expressed as:

P = σhg

Where: σ is the density of mercury, h is height of mercury in the barometer, and g is the acceleration due of gravity.

But, g = 9.81 m/[tex]s^{2}[/tex]

So that,

P = 1.36 x [tex]10^{4}[/tex] x 0.76 x 9.81

  = 101396.16 Pascal

P = 101.395 KPascal

The pressure at Mombasa is 101.396 KPascal.

Answer:

D) all of the above

Explanation:

All of the given choices are correct definition of what weight of a substance implies.

Weight is the vertical force on a body due to the gravitational attraction or pull.

  Weight  = mass x acceleration due to gravity

Mass of a body is directly proportional to its weight and so also is the gravity.

Mass is the amount of matter within a substance.

Weight is the force of gravity exerted by a body on another or a surface.

The reason why the weight of a body changes from place to place is mainly due to the gravitational pull

Answer:

[tex]U=5*10^7ft.Ib[/tex]

Explanation:

From the question we are told that

Weight  [tex]W= 10000bs[/tex]

Altitude [tex]H=5000ft[/tex]

Speed    [tex]V=125kts\\1kts=0.514m/s\\V=125*0.514=>64.25m/s[/tex]

Generally the equation for Potential energy ids mathematically given as

[tex]Potential\ Energy\ U=mgh[/tex]

[tex]U=Wh[/tex]

[tex]U=10000*5000[/tex]

[tex]U=5*10^7ft.Ib[/tex]

Complete Question:

an object on a number line moved from x = 12 m to x = 124 m and moved back to x = 98 m. the time interval for all the motion was 10 s. what was the average velocity of the object?

Answer:

v = 8.6 m/s

Explanation:

       [tex]v_{avg} =\frac{x_{f} -x_{o}}{t_{f} - t_{o} } (1)[/tex]

       [tex]v_{avg} =\frac{x_{f} -x_{o}}{t_{f} - t_{o} } =\frac{98 m -12 m}{10.0 s - 0 s } = \frac{86m}{10.0s} = 8.6 m/s (2)[/tex]