An X-Ray machine delivers a radiation dose of 5mRem/hr. at 3ft from the machine. How far will the X-Ray technician have to move to reduce his exposure to 2mRem/hr.? I1/I2 = (D2)2/(D1)2 -------> I1(D1)2 = I2(D2)2

Answer:

If x = A sin w t    where w is the angular frequency

then v = w A cos w t

Since KE = 1/2 m Vmax^2 and Vmax = w A     maximum KE

the total energy is proportional to A^2

Also, since the maximum potential energy is

PEmax = 1/2 K A^2    where the KE is zero (maximum amplitude)

one can again see that the total energy is proportional to A^2

Answer:

Explanation:

angular velocity

ω = 1.65 rad /s

radius R = 2.70 m

angular displacement = 8.70 rad

a )

New position vector in vector form

= R cos8.7 i + R sin8.7 j

= 2.7 cos8.7 i + 2.7 sin8.7 j

= 2.7 x .748 i + 2.7 x .663 j

= 2.01 i + 1.79 j

b )

8.7 radian = 180/π x 8.7 degree

= 498.72 degree

= 498.72 - 360

= 138.72 degree

It will be in second quadrant .

angle made with positive x - axis

= 138.72 degree .

c )

velocity

v = ω R

= 1.65 x 2.7

= 4.455 m /s

d )

It is moving in a direction making 138.72° with positive x direction .

e )

acceleration will be centripetal acceleration

= v²/ R  

= 4.455² / 2.7

= 7.35 m /s²

f ) force = mass x acceleration

= 3.8 x 7.35

= 27.93 N .

Answer:

The force is  [tex]F = 784 \ N[/tex]

Explanation:

From the question we are told that

      The mass of the man is  [tex]m = 70 \ kg[/tex]

      The mass of the beam is [tex]m_b = 10 \ kg[/tex]

Now from the question we can deduce that when this beam start to tip that both the force exerted by the weight of the man and that of the beam is been supported by the  right support so

 The force exerted on the right support is mathematically evaluated as

           [tex]F = (m + m_b) * g[/tex]

substituting values

         [tex]F = (70 + 10 ) * 9.8[/tex]

         [tex]F = 784 \ N[/tex]

The force exerted on the beam by the right support is 784 Newton.

Given the data in the question;

Force exerted on the beam by the right support; [tex]F = W = \ ?[/tex]

When the beam just starts to tip, the right support holds up the combined mass of the man and the beam.

Hence;

[tex]M_{net} = m_m + m_b\\\\M_{net} = 70kg + 10kg\\\\M_{net} = 80kg[/tex]

Now, To determine the force exerted on the beam by the right support, we use the general formula for weight or equation of force of gravity which is expressed as:

[tex]F = W = m * g[/tex]

Where m is mass and g represents the acceleration due to gravity( [tex]9.8m/s^2[/tex] )

We substitute our values into the equation

[tex]F = 80kg * 9.8m/s^2\\\\F = 784kg.m/s^2\\\\F = 784N[/tex]

Therefore, the force exerted on the beam by the right support is 784 Newton.

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Answer:

less than

Explanation:

The force of kinetic friction for a particular pair of interacting objects is always less than the force of static friction.

The force of static friction between two surfaces is always higher than the force of kinetic friction.

Answer:

The magnitude of the magnetic field is  [tex]B = 0.0890 \ T[/tex]

Explanation:

From the question we are told that

   The mass of the rod is  [tex]m =0.300 \ kg[/tex]

    The distance of separation is  [tex]d = 0.440 \ m[/tex]

     The current is  [tex]I = 15.0 \ A[/tex]

     The coefficient of friction is   [tex]\mu = 0.300[/tex]

Generally for the rod the rod to continue moving at a constant speed

   The frictional force must equal to the magnetic field force so

    [tex]F_m = F_f[/tex]

Where  [tex]F_m = B* I * d[/tex]

and     [tex]F_f = \mu * m * g[/tex]

   [tex]B*I *d = \mu * m * g[/tex]

=>    [tex]B = \frac{\mu * m * g }{I * d }[/tex]

substituting values

       [tex]B = \frac{0.2 * 0.300 * 9.8 }{ 15 * 0.440 }[/tex]

       [tex]B = 0.0890 \ T[/tex]

Answer:

large

Explanation:

Cumulus clouds is a term in metrology that defines the type of clouds which are characterized by its low altitude, puffy appearance, and fair-weather nature. They are generally considered as low-level clouds, with less than than 2,000m in altitude except they are the more vertical cumulus congestus form.

Thus, it can be noted that, the difference between the surface dew point temperature and the surface temperature is related to relative humidity. Hence, in a situation when there is a LARGE difference between the surface temperature and the surface dewpoint temperature, then the relative humidity is very low (e.g., 10%).

Therefore, the bases of developing convective cumulus clouds will be relatively higher at a location with a relatively LARGE difference between the surface temperature and surface dew point temperature.

Answer:

Explanation:

Accelerating voltage = 50 x 10³ V

energy created = q V where q is charge on electron and V is accelerating potential

So qV = 1/2 m v² , m is mass of electron and v is velocity

Putting values

1.6 x 10⁻¹⁹ x 50 x 10³ = 1/2 x 9.1 x 10⁻³¹ x v²

v² = 175.8 x 10¹⁴

v = 13.25 x 10⁷ m /s

Answer:

A = 0.02 m

Explanation:

The spring constant, k = 35.5 N/m

The attached mass, m = 5.50 kg

The expression for the external force, F =  (4.40 N)sin[(6.80 s⁻¹)t].....(1)

The general expression for the external force, F = F₀ sin (wt).............(2)

Comparing equations (1) and (2):

The forced frequency, [tex]\omega = 6.80 rad/s[/tex]

F₀ = 4.40 N

The natural frequency can be calculated using the formula:

[tex]\omega_0 = \sqrt{\frac{k}{m} } \\\\\omega_0 = \sqrt{\frac{35.5}{5.5} } \\\\\omega_0 = 2.54 rad/s[/tex]

The amplitude of oscillation of a spring-mass system in the steady state:

[tex]A = \frac{F_0}{m(\omega^2 - \omega_o^2)} \\\\A = \frac{4.4}{5.5(6.8^2 - 2.54^2)} \\\\A = 0.02 m[/tex]

Answer:

v₂ = 79.69 m/s

Explanation:

The initial diameter of the hose, d₁ = 3.0 cm = 0.03 m

Initial Cross Sectional Area, A₁ = πd₁²/4

A₁ = (π* 0.03²)/4

A₁ = 0.00071 m²

The initial speed of water from the hose, v₁ = 2.2 m/s

The diameter of the hose after blocking the end, d₂ = 0.50 cm = 0.005 m

Cross Sectional Area of the hose after blocking the end, A₂ = πd₂²/4

A₂ = (π* 0.005²)/4

A₂ = 0.0000196 m²

To get the speed, v₂, at which the water spray from the hose after blocking the end, we will use the continuity equation:

A₁v₁ = A₂v₂

0.00071 * 2.2 = 0.0000196 v₂

0.001562 = 0.0000196 v₂

v₂ = 0.001562/0.0000196

v₂ = 79.69 m/s

Answer:

Time needed for one revolution is 0.38 s

Explanation:

The formula for the frequency of rotation of a spaceship, to create the desired artificial gravity, is as follows:

f = (1/2π)√(a/r)

where,

f = frequency of rotation = ?

a = artificial gravity required = 0.5 g

g = acceleration due to gravity on surface of Earth = 9.8 m/s²

r = radius of ship = 35 mm/2 = 17.5 mm = 17.5 x 10⁻³ m

Therefore,

f = (1/2π)√[(0.5)(9.8 m/s₂)/(17.5 x 10⁻³ m)]

f = 2.66 Hz

Now, for the time required for one revolution, is given as:

Time Period = T = 1/f

T = 1/2.66 Hz

T = 0.38 s

The time required for one revolution to simulate the desired gravity is 0.38 s.

The frequency can be calculate by the formula

[tex]\bold {f = (\dfrac {1}{2\pi})\sqrt{ar}}[/tex]

where,

f - frequency of rotation = ?

a-  artificial gravity required = 0.5 g

g -  gravitational acceleration on surface of Earth = 9.8 m/s²

r -  radius of ship = 35 mm/2 = 17.5 mm = 17.5 x 10⁻³ m

Put the value in the equation,

[tex]\bold {f = \dfrac {1}{2\pi}\squrt {(0.5)(9.8\ m/s^2)}{(17.5 x 10^{-3} m)}}\\\\\bold {f = 2.66\ Hz}[/tex]

the time required for one revolution can be calculated as

[tex]\bold {T =\dfrac 1f}\\\\\bold {T = \dfrac 1{2.66}\ Hz}\\\\\bold {T = 0.38\ s}[/tex]

Therefore, the time required for one revolution to simulate the desired gravity is 0.38 s.

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Answer:

The study of charges in motion and their  interaction with magnetic fields is known as electromagnetism.

Any material with an unequal number of  electrons and or protons could generally be  termed as ion.

Explanation:

i hope this will help you :)

Answer:

The air-water interface is an example of boundary. The transmitted portion of the initial wave energy is way smaller than the reflected portion. This makes the boundary  wave hard to hear.

When both the source of the sound and your ears are located underwater, the sound is louder because the sound waves can travel directly to your ear.

Explanation:

The air-to-water sound wave transmission is inhibited because more of reflection than transmission of the wave occurs at the boundary. In the end, only about 30% of the sound wave eventually reaches underwater. For sound generated underwater, all the wave energy is transmitted directly to the observer. Sound wave travel faster in water than in air because, the molecules of water are more densely packed together, and hence can easily transmit their vibration to their neighboring molecules, when compared to air.

Answer: The air-water interface is an example of boundary. The (transmitted) portion of the initial wave is way smaller than the (reflected) portion. This makes the (transmitted) wave hard to hear.

When both the source of the sound and your ears are located underwater, the sound is louder because the sound waves can (travel directly to your ears.)

Explanation:

The part of the sound wave that is transmitted across the boundary between air and water is much smaller than the part of the wave that is reflected. This is what makes it hard to hear your friend knocking two rocks together above the surface.

When you and the rocks are underwater, the sound that comes from knocking the rocks together can travel directly to your ears rather than having to be transmitted across mediums.

Answer:

a conductor is an object or type of material that allows the flow of charge (electrical current) in one or more directions.

Explanation:

. Materials made of metal are common electrical conductors.

Answer:

a) 1.95 V

b) 1.87 mA

c) 0.115 A

Explanation:

Given that

Number of primary turns, N(p) = 480

Number of secondary turns, N(s) = 7.8

Velocity of primary turns, V(p) = 120 V

Velocity of secondary turns, V(s) = ?

Current in the primary, I(p) = ?

Current in the secondary, I(s) ?

To solve this question, we would be using the formula

V(s)/V(p) = N(s)/N(s), now substituting the values, we have

V(s) / 120 = 7.8 / 480

V(s) = (7.8 * 120) / 480

V(s) = 936 / 480

V(s) = 1.95 V

To find the current in the primary, remember ohms law?

I = V/R

I(s) = V(s) / R(s)

I(s) = 1.95 / 17

I(s) = 0.115 A

Now, remember the relationship between current and voltage

I(p)/I(s) = V(s)/V(p)

I(p) / 0.115 = 1.95 / 120

I(p) = (1.95 * 0.115) / 120

I(p) = 0.22425 / 120

I(p) = 0.00187 A

I(p) = 1.87 mA

Answer:

Their frequency is 111.22 Hz

Explanation:

Wavelength is the minimum distance between two successive points on the wave that are in the same state of vibration and is expressed in units of length (m).

Frequency is the number of vibrations that occur in a unit of time. Its unit is s⁻¹ or hertz (Hz).

The propagation speed of a wave is the quantity that measures the speed at which the wave's disturbance propagates throughout its displacement. The speed at which the wave propagates depends on both the type of wave and the medium through which it propagates. Relate wavelength (λ) and frequency (f) inversely proportional using the following equation:

v = f * λ.

Then the frequency can be calculated as: f=v÷λ

In this case:

Replacing:

[tex]f=\frac{3.37 \frac{m}{s} }{0.0303 m}[/tex]

Solving:

f=111.22 Hz

Their frequency is 111.22 Hz

Answer:

Explanation:

Radius of wheel = 1.2 m

A )

To know angular speed after t sec , we use the formula

ω = ω₀ + α t  , where ω₀ is initial velocity , α is angular acceleration

ω = 0 + 4.4 x 2

= 8.8 rad / s

v= ωR , v is tangential speed , ω is angular speed , R is radius of wheel .

= 8.8 x 1.2 = 10.56 m /s

B )

radial acceleration

Ar = v² / R

= 10.56² / 1.2

= 92.93 m /s²

Tangential acceleration

At = angular acceleration x radius

= 4.4 x 1.2 = 5.28 m /s²

Total acceleration

=  √ ( At² + Ar² )

=√ (5.28² +92.93²)

= 93 m /s²

C )

θ = ωt + 1/2 α t²     where θ is angular position after time t .

= 0 + .5 x 4.4 x 2²

= 8.8 rad

= 180x 8.8/ 3.14  = 504.45 degree

initial position = 57.3°

final position = 504 .45 + 57.3

= 561.75 °

= 561.75 - 360

= 201.75 ° .

Position of radius vector of point P will be at angle of 201.75 from horizontal axis .

Answer:

a. Dielectric constant, ε = 1.5 b. Electric susceptibility, χ = 0.5

Explanation:

a. Dielectric constant

Since the capacitance of the capacitor is increased by a factor of 1.5. Let its initial capacitance be C and its final capacitance after adding the material be C'.

Since C' = εC where ε = relative permittivity,

Also, C' = 1.5C

Comparing both equations for C', ε = 1.5.

Since ε = relative permittivity = dielectric constant,

dielectric constant = 1.5

So, the dielectric constant = 1.5

b. Electric susceptibility

The electric susceptibility χ is given by

χ = ε - 1 where ε = dielectric constant

Since ε = 1.5,

χ = ε - 1

χ = 1.5 - 1

χ = 0.5

So the electric susceptibility χ = 0.5

Answer:

The angular momentum (about the same axis) of the object is constant

Explanation:

Torque is the time time derivative of angular momentum.

τ = dL / dt

where;

dL  is the change in  angular momentum

τ is torque acting on the object

dt is change in time

when net torque acting on an object is zero, then

dL / dt = 0

Change in angular momentum (ΔL) is zero, therefore we can say that the angular momentum (L) is constant.

Thus, the angular momentum (about the same axis) of the object is constant.

Answer:

Explanation:

From,

1cm = [tex]10^{-2}m[/tex]

1mm = [tex]10^{-3}m[/tex]

1nanometer = [tex]10^{-9[/tex]

1micrometer = [tex]10^{-6[/tex]

Therefore,

A) [tex]10^0[/tex] meters = 1meter

B) [tex]10^2[/tex] cm = [tex]10^2 * 10^{-2} = 1meter[/tex]

C) [tex]10^4[/tex] mm = [tex]10^4 * 10^{-3} = 10meter[/tex]

D) [tex]10^5[/tex] micrometer = [tex]10^5 * 10^{-6} = 0.1meter[/tex]

E) [tex]10[/tex] nanometer = [tex]10 * 10^-9 = 1*10^{-8}[/tex]

Therefore 10nanometers is the shortest length

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Answer:

d. may be either greater, smaller, or equal to that observed inside the bus.

Explanation:

Answer:

"Upwards and towards the left" is the right answer.

Explanation:

The magnitude of the field will be:

⇒  [tex]E=\frac{kq}{r^2}[/tex]

And direction -> for negative charges, to positive charges, except charges.  

Thus the net field is upwards as well as to the left.

Answer:

[tex]$ \phi_{21} = \frac{\phi_{12}}{2} $[/tex]

Which means that the flux through each loop of the second coil is half as much as flux through each loop of first coil.

Explanation:

The flux through each loop of the first coil due to current in the second coil is,

[tex]\phi_{12} = \phi[/tex]

The number of loops in the first coil is

no. of loops = 2N

Total flux passing through the first coil is

[tex]\phi_{12} = 2N\phi[/tex]

The flux through each loop of the second coil due to current in the first coil is,

[tex]\phi_{21} = \phi[/tex]

The number of loops in the second coil is

no. of loops = N

Total flux passing through the second coil is

[tex]\phi_{21} = N\phi[/tex]

Comparing both

[tex]\phi_{12} = \phi_{21} \\\\ 2N\phi = N\phi\\\\\phi_{21} = \frac{\phi_{12}}{2}[/tex]

Which means that the flux through each loop of the second coil is half as much as flux through each loop of first coil.

Answer:

B. Glass

Explanation:

An electrical insulator is a substance that does not conduct electricity.

Glass has tightly bounded electrons, that is why it is an insulator of electricity.

Hey there! The answer to your question is below.

The correct answer would be B.GLASS

Glass is a insulator and rubber too

Glass, wood, plastic and more are all insulators

So the answer would be B. Glass

Hope this helps!

By: xBrainly

Answer:

a) the magnitude of the force is

F= Q([tex]\frac{kqs}{r^3}[/tex]) and where k = 1/4πε₀

F = Qqs/4πε₀r³

b)  the magnitude of the torque on the dipole

τ = Qqs/4πε₀r²

Explanation:

from coulomb's law

E = [tex]\frac{kq}{r^{2} }[/tex]

where k = 1/4πε₀

the expression of the electric field due to dipole at a distance r is

E(r) = [tex]\frac{kp}{r^{3} }[/tex] , where p = q × s

E(r) = [tex]\frac{kqs}{r^{3} }[/tex] where r>>s

a) find the magnitude of force due to the dipole

F=QE

F= Q([tex]\frac{kqs}{r^3}[/tex])

where k = 1/4πε₀

F = Qqs/4πε₀r³

b) b) magnitude of the torque(τ) on the dipole is dependent on the perpendicular forces

τ = F sinθ × s

θ = 90°

note: sin90° = 1

τ = F × r

recall  F = Qqs/4πε₀r³

∴ τ = (Qqs/4πε₀r³) × r

τ = Qqs/4πε₀r²

Part A: The expression of the force on the dipole is [tex]F = \dfrac {Qqs}{4 \pi \epsilon_0 r^3}[/tex].

Part B: The expression of the torque on the dipole is [tex]\tau = \dfrac {Qqs}{4\pi\epsilon_0 r^2}[/tex].

Given that a point charge Q is held at a distance r from the center of a dipole that consists of two charges ±q separated by a distance s. Also, r>>s.

Part A

The electric field due to dipole at a distance r is given below.

[tex]E_r = \dfrac {qs}{4\pi \epsilon_0 r^3}[/tex]

The magnitude of the force can be given as below.

[tex]F = QE_r[/tex]

[tex]F = \dfrac {Qqs}{4 \pi \epsilon_0 r^3}[/tex]

Hence the expression of the force on the dipole is [tex]F = \dfrac {Qqs}{4 \pi \epsilon_0 r^3}[/tex].

Part B

The torque on the dipole will dependent on the perpendicular forces on the dipole. The expression of the torque is given below.

[tex]\tau = F \times r \times sin \theta[/tex]

For the perpendicular forces, θ = 90°. Hence the torque is given below.

[tex]\tau = F\times r[/tex]

[tex]\tau = \dfrac {Qqs}{4 \pi \epsilon_0 r^3} \times r[/tex]

[tex]\tau = \dfrac {Qqs}{4\pi\epsilon_0 r^2}[/tex]

Hence the expression of the torque on the dipole is [tex]\tau = \dfrac {Qqs}{4\pi\epsilon_0 r^2}[/tex].

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Answer:

Option A. 11

Explanation:

The atomic number of an element does not change.

Recall:

Atomic number = proton number

If the atom is neutral, then,

Proton number = electron number

Since the element is sodium, then, the atomic number of sodium–25 is 11.

Also, we were told to obtain the electrons of a neutral atom of sodium–25

Therefore,

Atomic number = proton number = 11

Since the atom is neutral,

Proton number = electron number = 11

Answer:

A. 11

Explanation:

A neutral atom of sodium-25 has the same number of protons and electrons. Since it has 11 protons, it also must have 11 electrons!

Answer:

E = (-3.61^i+1.02^j) N/C

magnitude E = 3.75N/C

Explanation:

In order to calculate the electric field at the point P, you use the following formula, which takes into account the components of the electric field vector:

[tex]\vec{E}=-k\frac{q}{r^2}cos\theta\ \hat{i}+k\frac{q}{r^2}sin\theta\ \hat{j}\\\\\vec{E}=k\frac{q^2}{r}[-cos\theta\ \hat{i}+sin\theta\ \hat{j}][/tex]              (1)

Where the minus sign means that the electric field point to the charge.

k: Coulomb's constant = 8.98*10^9Nm^2/C^2

q = -4.28 pC = -4.28*10^-12C

r: distance to the charge from the point P

The point P is at the point (0,9.83mm)

θ: angle between the electric field vector and the x-axis

The angle is calculated as follow:

[tex]\theta=tan^{-1}(\frac{2.79mm}{9.83mm})=74.15\°[/tex]

The distance r is:

[tex]r=\sqrt{(2.79mm)^2+(9.83mm)^2}=10.21mm=10.21*10^{-3}m[/tex]

You replace the values of all parameters in the equation (1):

[tex]\vec{E}=(8.98*10^9Nm^2/C^2)\frac{4.28*10^{-12}C}{(10.21*10^{-3}m)}[-cos(15.84\°)\hat{i}+sin(15.84\°)\hat{j}]\\\\\vec{E}=(-3.61\hat{i}+1.02\hat{j})\frac{N}{C}\\\\|\vec{E}|=\sqrt{(3.61)^2+(1.02)^2}\frac{N}{C}=3.75\frac{N}{C}[/tex]

The electric field is E = (-3.61^i+1.02^j) N/C with a a magnitude of 3.75N/C

Answer:

It goes down.

The water level remain the same.

Explanation:

This can be explained using Archimedes principle which states that a body fully or partially submerged in a fluid is acted by an upward bouyant force which is equal to the weight of the fluid the body displaced.

The wood will only sink if the weight of the wood is greater than the weight of the fluid the wood displaced, but the weight of the wood is equal to the weight of fluid displaced, therefore the wood will float.

Therefore, the weight of the wood is the same as the weight of the fluid displaced, so the wood will be at the same level as the water.

If the iron is removed, the level of the water goes down because iron weight is bigger than the water displaced and it tends to increase the water level but since it is removed, the water level will decrease.

Answer:

The horizontal velocity vector of the canonball does not change at all, but is constant throughout the flight.

Explanation:

First, I'll assume this is a projectile simulation, since no simulation is shown here. That been the case, in a projectile flight, there is only a vertical component force (gravity) acting on the body, and no horizontal component force on the body. The effect of this on the canonball is that the vertical velocity component on the canonball goes from maximum to zero at a deceleration of 9.81 m/s^2, in the first half of the flight. And then zero to maximum at an acceleration of 9.81 m/s^2 for the second half of the flight before hitting the ground. Since there is no force acting on the horizontal velocity vector of the canonball, there will be no acceleration or deceleration of the horizontal velocity component of the canonball. This means that the horizontal velocity component of the canonball is constant throughout the flight

Explanation:

It is given that,

The distance between the radio and the radio station is 174 m

We need to find how many wavelengths of the radio waves are there between the transmitter and radio receiver if the woman is listening to an AM radio station broadcasting at 1540 kHz.

f = 1540 kHz

Wavelength,

[tex]\lambda=\dfrac{c}{f}\\\\\lambda=\dfrac{3\times 10^8}{1540\times 10^3}\\\\\lambda=194.8\ m[/tex]

Let there are n wavelengths of the radio waves. So,

[tex]n=\dfrac{d}{\lambda}\\\\n=\dfrac{174}{194.8}\\\\n=0.89\ \text{wavelengths}[/tex]

There are 0.89 wavelengths.

Answer:

The excess charge is [tex]Q = 3.5 *10^{-7} \ C[/tex]

Explanation:

From the question we are told that

      The diameter is [tex]d = 45 \ cm = 0.45 \ m[/tex]

       The potential of the surface is [tex]V = 14 \ kV = 14 *10^{3} \ V[/tex]

The radius of the sphere is  

           [tex]r = \frac{d}{2}[/tex]

substituting values

          [tex]r = \frac{0.45}{2}[/tex]

         [tex]r = 0.225 \ m[/tex]

The potential on the surface is mathematically represented as  

          [tex]V = \frac{k * Q }{r }[/tex]

Where k is coulomb's constant with value  [tex]k = 9*10^{9} \ kg\cdot m^3\cdot s^{-4} \cdot A^{-2}.[/tex]

  given from the question that there is no other charge the Q is the excess charge  

Thus  

        [tex]Q = \frac{V* r}{ k}[/tex]

substituting values

        [tex]Q = \frac{14 *10^{3} 0.225}{ 9*10^9}[/tex]

        [tex]Q = 3.5 *10^{-7} \ C[/tex]