friction always opposes the _____​

Answer:

ω₁ = 2.2 rev/s

Explanation:

Conservation of angular momentum

moment of inertia uniform disk is ½mR²

moment of inertia uniform rod about an end mL²/3

We can think of our rod as two rods of mass m/2 and length R

L = ½mR²ω₀

L = (½mR² + 2(m/2)R²/3)ω₁

ω₁ = ω₀(½mR² / (½mR² + mR²/3))

ω₁ = ω₀(½  / (½  + 1/3))

ω₁ = 0.6ω₀

ω₁ = 2.16

Answer:

One can write F = K d^-2  where K = G M m

So dF/dd = -2 K d^-3 =   -2 K / d^3    (As d increases F decreases - it is opposite to the direction of F)

Answer:

    T₂ > T₁ > T₃ >T₄

Explanation:

In a simple harmonic motion the angular velocity is

         w = [tex]\sqrt{\frac{k}{m} }[/tex]

angular velocity and period are related

         w = 2π / T

we substitute

         T = [tex]2 \pi \ \sqrt{\frac{m}{k} }[/tex]

let's find the period for each case

a) mass m

   spring constant k

          T₁ = 2π [tex]\sqrt{\frac{m}{k} }[/tex]

b) mass 2m

   spring constant k

          T₂ = 2π [tex]\sqrt{\frac{2m}{k} }[/tex]

          T₂ = T₁ √2

          T₂ = T₁ 1.41

c) masses 3m

   spring constant 6k

          T₃ = 2π [tex]\sqrt{\frac{3m}{6k} }[/tex]

          T₃ = 2π [tex]\sqrt{\frac{m}{k} } \ \sqrt{0.5}[/tex]

          T₃ = T₁ 0.707

d) mass m

    spring constant 4k

          T₄ = 2π [tex]\sqrt{ \frac{m}{4k} }[/tex]

          T₄ = 2π [tex]\sqrt{\frac{m}{k} } \ \sqrt{0.25}[/tex]

          T₄ = T₁ 0.5

now let's order the periods in decreasing order

           T₂ > T₁ > T₃ >T₄

Answer:

The length of the wire is "1.93 m".

Explanation:

Given:

Current,

I = 0.66 A

Angle,

[tex]\Theta[/tex] = 58°

Magnetic field of magnitude,

F = [tex]5.5\times 10^{-5}[/tex] N

The length of the wire will be:

⇒ [tex]F = B\times I\times L\times Sin \Theta[/tex]

or,

⇒ [tex]L = \frac{F}{B\times I\times Sin \theta}[/tex]

By putting the values, we get

       [tex]=\frac{5.5\times 10^{-5}}{0.66\times 5.1\times 10^{-5}\times Sin \ 58^{\circ}}[/tex]

       [tex]=\frac{5.5}{2.828}[/tex]

       [tex]=1.93 \ m[/tex]

Answer:

Explanation:

According to the Fleming's right hand rule, if we spread our right hand such that the thumb, fore finger and the middle finger are mutually perpendicular to each other, then the thumb indicates the direction of force, fore finger indicates the direction of magnetic field, then the middle finger indicates the direction of induced current.

According to the Lenz's law, the direction of induced emf is such that it always opposes the cause due to which it is produced.

Explanation:

N2 + H2 --> NH3

balance them:

N2 + 3 H2 --> 2 NH3

so if 6 moles of N2 react, 12 moles of NH3 will form.

(you have to look at the big number in front, in this case its N2 and 2 NH3, therefore the amount of N2 will produce double the amount of NH3 )

Answer:

1.37 mm²

Explanation:

From the image attached below:

Let's take a look at the two rays r and r' hitting the same mirror from two different positions.

Let x be the distance between these rays.

[tex]d_o =[/tex] distance between object as well as the mirror

[tex]d_{eye}[/tex] = distance between mirror as well as the eye

Thus, the formula for determining the distance between these rays can be expressed as:

[tex]x = 2d_o tan \theta[/tex]

where; the distance between the eye of the observer and the image is:

[tex]s = d_o + d_{eye}[/tex]

Then, the tangent of the angle θ is:

[tex]tan \theta = \dfrac{R}{d_o+d_{eye}}[/tex]

replacing [tex]tan \theta = \dfrac{R}{d_o+d_{eye}}[/tex] into [tex]x = 2d_o tan \theta[/tex], we have:

[tex]x = 2d_o \Big( \dfrac{R}{d_o+d_{eye}}\Big)[/tex]

[tex]x = 2(10) \Big( \dfrac{0.25}{10+28}\Big)[/tex]

[tex]x = 20\Big( \dfrac{0.25}{38}\Big) cm[/tex]

x = (0.13157 × 10) mm

x = 1.32 mm

Finally, the area A = π r²

[tex]A = \pi(\frac{x}{2})^2[/tex]

[tex]A = \pi(\frac{1.32}{2})^2[/tex]

A = 1.37 mm²

Complete Question

Partial tides __________.

Question 7 options:  

a. represent various components of local tides that are resolved mathematically  

b. are added together to predict the height and timing of astronomical tides  

c. consist of 4 components due to the influence of celestial bodies  

d. consist of up to 60 components due to astronomical and non-astronomical factors  

e. All of the above except c are correct.

Answer:

Option E

Explanation:

Generally

Partial tides represent various components of local tides that are resolved mathematically

Partial tides  are added together to predict the height and timing of astronomical tides

Partial tides consist of up to 60 components due to astronomical and non-astronomical factors

But Partial tides do not consist of 4 components due to the influence of celestial bodies

Therefore

All of the above except c are correct.

Option E

Answer:

Explanation:

The law of reflection says that the reflected angle (measured from a vertical line to the surface  called the normal) is equal to the reflected angle measured from the same normal line.

All other properties of reflection flow from this one statement.

Answer:

In sof the friction with the nylon is very small and the current with the line e is largeummary

Explanation:

When we rub the shoes against the carpet, static electricity is produced, when you touch the metal knob you close the circuit and the current can circulate to three of the body, the value of this current is of the order of micro volts, for which a small discharge, the power that circulates through the body is very small of the order of 0.005 A

When you touch the power line, the voltage may be small, but the amount of current that can generate them is of the order of tens of amps, the electric shock is much greater per location.

In general there is a rule that if the body resumes more than P = 4000W the discharge could be fatal.

In sof the friction with the nylon is very small and the current with the line e is largeummary, the difference is that the current at the stop , so the paper that passes through the body is large and can be dangerous.

In contact with metal doorknob, get a mild shock  while with power line of same voltage, fatal the body as the amount of current is more.

When the two materials are rubbed each other, then the electric charged generated between them.

This charging of materials, due to the rubbing of two materials against each other, is called the charging by friction.

It is easy to produce a potential difference of several thousand volts between the body and the floor by scuffing your shoes across a nylon carpet.

In this case, the potential difference may be higher, but the value of current is very low. Thus, when the body touches a metal doorknob, it will get a mild shock.

Now, in another case, the contact with a power line of comparable voltage would probably be fatal. This is because in the power line the amount of current is much higher.

Hence, in contact with metal doorknob, get a mild shock  while with power line of same voltage, fatal the body as the amount of current is more.

Learn more about the charging by friction here;

https://brainly.com/question/8418256

Answer:

Modern technology is the advancement of old technology with adjustments.

1. Ghana is still developing economically and modern  infrastructure is not yet well established.

2. Ghana has Environmental- health concerns which contribute to the lack of improvement of technology in Ghana.

3.  Youth unemployment is prevalent therefore contributing to lack of improvement of technology in Ghana.

Explanation:

Ghana is a developing country with rising debt payments which could very well contribute as whole to the lack of improvement of technology in Ghana.

Answer:

D

Explanation:

Anyone could be leaning forward toward the speaker but be distracted and I believe if you're paying attention to the speaker, you would ask questions to make sure you're understanding what they are speaking

Answer:

A

.............................

Answer:

The correct option is B. 7.5 * 10¹⁴ Hz

Explanation:

Frequency = (speed) / (wavelength)

= (3 x 10⁸ m/s) / (4 x 10⁻⁷ m)

= (3/4 x 10¹⁵) ( m / m - s )

= (0.75 x 10¹⁵) /sec

= 7.5 x 10¹⁴ Hz

= 750,000 GHz

Answer:

Mark Brainliest please

answer is

Explanation:

For any wave,              

                          Frequency = (speed) / (wavelength)

                                             = (3 x 10⁸ m/s) / (4 x 10⁻⁷ m)

                                             = (3/4 x 10¹⁵)  ( m / m - s )

                                             = (0.75 x 10¹⁵)  /sec

                                             =  7.5 x 10¹⁴  Hz

                                             =   750,000 GH

Answer:

1. A. Safety measures in handling machines

2. C. One lane, follow the traffic signal

3. D. Internal and external forces contribute to the formation of various surface features of the earth.

4. D. Tsunami

Explanation:

1. Safety measures are precautions that must be taken to avoid injuries when handling some potentially dangerous equipment. They are meant to protect us from harm.

2. If a part of the road is to be sealed up temporarily, road users should be alerted that there is just one lane ahead. Therefore, they should follow the traffic signal.

3. The pressure exerted on the earth through phenomena like plate tectonics, earthquakes, etc., causes the eruption and formation of different features on the earth.

4. A tsunami is a giant ocean wave caused by earthquakes and volcanic eruptions that occur under the sea. They occur with a lot of speed and cause an overflow of water onto land.

Answer:

a) The laser device

b) The tape

Explanation:

First, there is a need to understand what accuracy and precision mean.

Accuracy is the closeness of a measurement to its true (pre-determined) value.

Precision is the closeness of repeated measurements to each other.

Since 1 feet = 12 inches, then, 5 feet and 5.2 inches would be equivalent to 65.2 inches. This value represents the true value of my height.

The tape measured the height as 65 3/8, which is equivalent to 65.375 inches.

The laser device measured the height as 65.31.

Error = true value - measured value

Absolute error from the tape = 65.2 - 65.375

                                       = -0.175 inches

Absolute error from laser device = 65.2 - 65.31

                                 = -0.11

a) The magnitude of error from the tape is more than that of the laser device. Hence, the laser device is said to be more accurate.

b) Even though there were just single readings from both instruments, the tape can be read to the nearest 1/8 of an inch and as such, can give more precisive measurements than the laser device.

Answer:

a)  fem = - 2.1514 10⁻⁴ V,  b) I = - 64.0 10⁻³ A, c)    P = 1.38  10⁻⁶ W

Explanation:

This exercise is about Faraday's law

         fem = [tex]- \frac{ d \Phi_B}{dt}[/tex]

where the magnetic flux is

        Ф = B x A

the bold are vectors

        A = π r²

we assume that the angle between the magnetic field and the normal to the area is zero

         fem = - B π 2r dr/dt = - 2π B r v

linear and angular velocity are related

        v = w r

        w = 2π f

        v = 2π f r

we substitute

        fem = - 2π B r (2π f r)

        fem = -4π² B f r²

For the magnetic field of Jupiter we use the equatorial field B = 428 10⁻⁶T

we reduce the magnitudes to the SI system

       f = 2 rev / s (2π rad / 1 rev) = 4π Hz

we calculate

       fem = - 4π² 428 10⁻⁶ 4π 0.10²

       fem = - 16π³ 428 10⁻⁶ 0.010

       fem = - 2.1514 10⁻⁴ V

for the current let's use Ohm's law

        V = I R

        I = V / R

         I = -2.1514 10⁻⁴ / 0.00336

         I = - 64.0 10⁻³ A

Electric power is

        P = V I

        P = 2.1514 10⁻⁴ 64.0 10⁻³

        P = 1.38  10⁻⁶ W

Solution :

Owing to the continuous attraction and repulsion force caused by the magnet or the electromagnet around the core of the motor produces a unidirectional torque whose direction is given by the Lorentz force, [tex]$F=q(\vec v \times \vec B)$[/tex], and thus the torque causes the rotation of the electric motor.

Removing half the insulation from the coil makes it to rotate just half a turn. When the half insulation is removed, the coil turns half and the rest of the time the connection terminates. The rest half turn will be provided by the angular momentum. Now after this half turn by the angular momentum, the connections will again be connected and again the torque will work on it to rotate the half turn. This continues and the motor rotates.

Answer:

a) ε = 14.7 μv

b) ε = 21 μv

Explanation:

Given the data in the question;

Diameter of solenoid; d = 3 cm

radius will be half of diameter,  so, r = 3 cm / 2 = 1.5 cm = 1.5 × 10⁻² m

Number of turns; N = 40 turns per cm = 4000 per turns per meter

Current; [tex]I[/tex] = 0.235 A

change in time Δt = 0.40 sec

Now,

We determine the magnetic field inside the solenoid;

B = μ₀ × N × [tex]I[/tex]  

we substitute

B = ( 4π × 10⁻⁷ Tm/A ) × 4000 × 0.235  

B = 1.1881 × 10⁻³ T

Now, Initial flux through the coil is;

∅₁ = NBA = NBπr²  

and the final flux  

∅₂ = 0        

so, the εmf induced ε = -Δ∅/Δt = -( ∅₂ - ∅₁ ) / Δt

= -( 0 - NBπr² ) / Δt  

= NBπr² / Δt    

a)

for N = 7

ε = [ 7 × ( 1.1881 × 10⁻³ ) × π( 1.5 × 10⁻² )² ] / 0.40

ε = 14.7 × 10⁻⁶ v

ε = 14.7 μv      

b)

for N = 10

ε = [ 10 × ( 1.1881 × 10⁻³ ) × π( 1.5 × 10⁻² )² ] / 0.40

ε = 21 × 10⁻⁶ v

ε = 21 μv  

Answer:

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Explanation:

Explanation:

Hi Linda,

How's it going?

Sorry I haven't been in touch for such a long time but I've had exams so I've been studying every free minute. Anyway, I'd love to hear all your news and I'm hoping we can get together soon to catch up. We just moved to a bigger flat so maybe you can come and visit one weekend?

How's the new job?

Looking forward to hearing from you!

Helga

Answer:

(a) 5.46 C

(b) 3.4125 x 10^19

Explanation:

q' = 1.08 C, q'' = 6.74 C, q''' = 4.61 C, q'''' = 9.41 C

When the charges are in contact to each other.

(a) So, the net charge is

[tex]q = \frac{q' + q'' + q''' + q''''}{4}[/tex]

[tex]q = \frac{1.08+6.74+4.61+9.41}{4}\\\\q = 5.46 C[/tex]

(b) As the charge is positive in nature, so the protons are there. The number of protons is

[tex]n = \frac{q}{e}\\\\n = \frac{5.46}{1.6\times 10^{-19}}\\\\n = 3.4125\times 10^{19}[/tex]

Answer:

Explanation:

Equilibrium is a state in which the algebraic sum of all forces acting on an object is zero. Thus the object has no force acting on it. The types are: stable, unstable and neutral equilibrium. While a torque is a turning force which are equal but acts in an opposite direction. When applied to on object, it constitute a turning effect. Example is the force applied on a tap, handle wheel of a car etc.

In the given question, the condition stated shows that the stick would experience a torque, thus not in equilibrium. Since the forces at its ends are in opposite directions, then it continues to rotate about its axis.

Answer:

a)[tex]L=0.00142H[/tex]

b) [tex]C=2.65*10^{-12}[/tex]

Explanation:

From the question we are told that:

Frequency[tex]F=13kHz[/tex]

Current [tex]I=0.14A[/tex]

Capacitor[tex]C_e=1.4*10^{-5}J[/tex]

Generally the equation for Energy in the inductor is mathematically given by

Where L is now subject

[tex]L=\frac{2C_e}{I^2}[/tex]

[tex]L=\frac{2*1.4*10^{-5}}{(0.14)^2}[/tex]

[tex]L=0.00142H[/tex]

Generally the equation for Value of Capacitor is mathematically given by

[tex]C=\frac{1}{(2 \pi f)^2} L[/tex]

[tex]C=\frac{1}{(2 3.142 13*10^3Hz)^2} *0.00142[/tex]

[tex]C=2.65*10^{-12}[/tex]

Answer:

The principle of a potentiometer is that the potential dropped across a segment of a wire of uniform cross-section carrying a constant current is directly proportional to its length. The potentiometer is a simple device used to measure the electrical potentials (or compare the e.m.f of a cell).

Explanation:

I hope it will help you

Explanation:

some thing inside a resistor

Answer:

The speed at B is 16.18 ft/s .

Explanation:

Speed at A, u = 11 ft/s

Speed at C, v' = 18 ft/s

Time from A to C = 5 s

Time from B to C = 1.3 s

Let the speed of car at B is v.

Let the acceleration is a.

From A to B

Use first equation of motion

v = u + a t

18 = 11 + a x 5

a = 1.4 ft/s^2

Let the time from A to B is t' .

t' = 5 - 1.3 = 3.7 s

Use first equation of motion from A to B

v = 11 + 1.4 x 3.7 = 16.18 ft/s  

Answer:

No ejection of photo electron takes place.

Explanation:

When a photon of suitable energy falls on cathode, then the photoelectrons is emitted from the cathode. This phenomenon is called photo electric effect.

The minimum energy required to just  eject an electron is called work function.

The photo electric equation is

E = W + KE

where, E is the incident energy, W is the work function and KE is the kinetic energy.

W = h f

where. h is the Plank's constant and f is the threshold frequency.

Now, when the violet light is falling, no electrons is ejected. When the red light is falling, whose frequency is less than the violet light, then again no photo electron is ejected from the metal surface.

Answer:

1.74×10⁻³ m

Explanation:

Applying,

ε = Stress/strain............. Equation 1

Where ε = Young's modulus

But,

Stress = F/A.............. Equation 2

Where F = Force, A = Area

Strain = e/L.............. Equation 3

e = extension, L = Length.

Substitute equation 2 and 3 into equation 1

ε = (F/A)/(e/L) = FL/eA............. Equation 4

From the question,

Given: F = 285 N, L = 29 cm = 0.29 m, ε = 5.00×10⁹ N/m²,

A = πd²/4 = 3.14(0.0011²)/4 = 9.4985×10⁻⁶ m²

Substitute these values into equation 4

5.00×10⁹ = (285×0.29)/(9.4985×10⁻⁶×e)

Solve for e

e = (285×0.29)/(5.00×10⁹×9.4985×10⁻⁶)

e = 82.65/4.74925×10⁴

e = 1.74×10⁻³ m