What kind of energy is in a moving skateboard

Answer:

The force will be "9.8 N".

Explanation:

The given values are:

mass,

m = 0.7 kg

M = 2

g = 9.8

Now,

⇒  [tex]\tau = T \alpha[/tex]

then,

⇒  [tex]\frac{1}{2}mR^2(\frac{1}{R}\frac{dv}{dt}) =M(g-a_t)R[/tex]

⇒  [tex]\frac{1}{2}m \ a_t=m(g-a_t)[/tex]

⇒  [tex]a_t=\frac{2g}{(\frac{m}{M} +2)}[/tex]

On substituting the values, we get

⇒      [tex]=\frac{2\times 9.8}{\frac{0.7}{2} +2}[/tex]

⇒      [tex]=8.34 \ m/s[/tex]

hence,

⇒  [tex]T=mg+M(g-a_t)[/tex]

On substituting the values, we get

⇒      [tex]=0.7\times 9.8+2(9.8-8.34)[/tex]

⇒      [tex]=6.86+2(1.46)[/tex]

⇒      [tex]=6.86+2.92[/tex]

⇒      [tex]=9.8 \ N[/tex]

Answer:

A person that consistently runs 3 meters evert second

Explanation:

Because as a human walks 3 meters every 1 second it isn't consider uniform. It has to be in a erect motion

Answer:

i. 0.2 N ii. 30°

Explanation:

(i) Calculate the magnitude and direction of force on X, when a current of 4A is passed through it.

The magnetic force F = BILsinФ where B = magnetic field strength = 0.1 T, I = current = 4 A and L= length of conductor = 0.5 m. Since the conductor X of length 0.5m is held along the positive X-axis and situated in a uniform horizontal magnetic field of 0.1T which is pointing towards the positive Y-axis, both B and L are perpendicular to each other. So, Ф = 90°

So, F = BILsinФ

F = 0.1 T × 4 A ×0.5 m × sin90°

F = 0.1 T × 4 A ×0.5 m × 1

F = 0.2 N

(ii) Through what angle must X be turned in a vertical plane so that the force on X is halved

If F' = BILsinФ' where Ф'=the new angle, and BIL = F

F'/F = sinФ'

Since F'/F = 1/2

sinФ' = 1/2

Ф' = sin⁻¹(1/2) = 30°

Answer:

[tex]65.6\ \text{J/m}^3[/tex]

[tex]0.11\ \text{J}[/tex]

Explanation:

B = Magnetic field = [tex]\mu_0 \dfrac{N}{l}I[/tex]

[tex]\mu_0[/tex] = Vacuum permeability = [tex]4\pi10^{-7}\ \text{H/m}[/tex]

N = Number of turns = 1270

[tex]l[/tex] = Length of solenoid = 93.9 cm = 0.939 m

[tex]I[/tex] = Current = 7.8 A

A = Area of solenoid = [tex]17.3\ \text{cm}^2[/tex]

Energy density of a solenoid is given by

[tex]u_m=\dfrac{B^2}{2\mu_0}\\\Rightarrow u_m=\dfrac{(\mu_0 \dfrac{N}{l}I)^2}{2\mu_0}\\\Rightarrow u_m=\dfrac{\mu_0N^2I^2}{2l^2}\\\Rightarrow u_m=\dfrac{4\pi\times 10^{-7}\times 1230^2\times 7.8^2}{2\times 0.939^2}\\\Rightarrow u_m=65.6\ \text{J/m}^3[/tex]

The energy density of the magnetic field inside the solenoid is [tex]65.6\ \text{J/m}^3[/tex]

Energy is given by

[tex]U_m=u_mAl\\\Rightarrow U_m=65.6\times 17.3\times 10^{-4}\times 0.939\\\Rightarrow U_m=0.11\ \text{J}[/tex]

The total energy in joules stored in the magnetic field is [tex]0.11\ \text{J}[/tex].

Answer: The half-life is the amount of time it takes for a given isotope to lose half of its radioactivity. If a radioisotope has a half-life of 14 days, half of its atoms will have decayed within 14 days. In 14 more days, half of that remaining half will decay, and so on.

The correct statement about the wind is:

Wind is the movement of air currents in relation to the Earth's surface, which is caused by pressure differences and air movement.

Therefore, we can conclude that the wind is the current of air that occurs in the atmosphere due to natural causes, from high pressure areas to low pressure areas.

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Answer:

a) f = 4.76 10¹⁴ Hz, b) d = 2.73 10⁻⁴ m, c) θ = 6.923 10⁻³ rad

Explanation:

a) In this problem the frequency of light is asked, let's use the relationship between the speed of the wave, its wavelength and its frequency

           c = λ f

           f = c /λ

           f = [tex]\frac{3 \ 10^8}{630 \ 10^{-9}}[/tex]

           f = 4.76 10¹⁴ Hz

b) slit separation (d)

the expression for the constructive interference of the double-slit experiment is

          d sin  θ = m λ

let's use trigonometry

          tan θ = y / L

          tan θ = [tex]\frac{sin \theta}{cos \theta}[/tex]

in general the angles are small, so we can approximate

          tan θ = sin θ

          tan θ = y/L

we substitute

          d y / L = m λ

          d = m L λ / y

we calculate

          d = 3  1.3  630 10⁻⁹ /0.90 10⁻²

          d = 2.73 10⁻⁴ m

c) the angle

           tan θ = y / L

           θ = tan⁻¹ y / L

           θ = tan⁻¹ 0.9 10⁻² / 1.3

           θ = tan⁻¹ 6,923 10⁻³

let's find the angle in radians

           θ = 6.923 10⁻³ rad

Complete question is;

The frequency and wavelength of EM waves can vary over a wide range of values. Scientists refer to the full range of frequencies that EM radiation can have as the electromagnetic spectrum. Electromagnetic waves are used extensively in modern wireless technology. Many devices are built to emit and/or receive EM waves at a very specific frequency, or within a narrow band of frequencies. Here are some examples followed by their frequencies of operation:

garage door openers: 40.0 MHz

standard cordless phones: 40.0 to 50.0 MHz

baby monitors: 49.0 MHz

FM radio stations: 88.0 to 108 MHz

cell phones: 800 to 900 MHz

Global Positioning System: 1227 to 1575 MHz

microwave ovens: 2450 MHz

wireless internet technology: 2.4 to 2.6 GHz

Which of the following statements correctly describe the various applications listed above? Check all that apply.

a.) All these technologies use radio waves, including low-frequency microwaves.

b.) All these technologies use radio waves, including high-frequency microwaves.

c.) All these technologies use a combination of infrared waves and high-frequency microwaves.

d.) Microwave ovens emit in the same frequency band as some wireless Internet devices.

e.) The radiation emitted by wireless Internet devices has the shortest wavelength of all the technologies listed above.

f.) All these technologies emit waves with a wavelength in the range of 0.10 to 10.0 m.

g.) All the technologies emit waves with a wavelength in the range of 0.01 to 10.0 km.

Answer:

B, D, E, F are the correct statements.

Explanation:

Looking at the options;

A) This is true because radio waves are electromagnetic radiation being used today in television, mobile phones, radios and other areas of communication technologies. And the examples given to us fall in the category of technologies that use radio waves.

B) microwaves usually have long wavelengths and low frequencies. However, sometimes they could have high frequencies usually more than radio waves. Thus, this option is correct.

C) This option is wrong because it's not all the listed technologies that use combination of infrared waves and high-frequency microwaves.

D) we are given the frequency of microwave ovens as 2450 MHz.

Converting to GHz gives; 2.45 GHz.

We are told that wireless internet technology has frequency between 2.4 to 2.6 GHz. Thus, microwave frequency falls in the same range as wireless internet technology and thus the statement is true.

E) we know that wavelength is inversely proportional to frequency. This means that the higher the frequency, the shorter the wavelength.

In the frequencies given to us, wireless internet technology have the highest frequency which means they have the shortest wavelength. The statement is true.

F) from the frequencies given to us, the smallest is garage door openers = 40.0 MHz = 40 × 10^(6) Hz while the biggest is 2.6 GHz = 2.6 × 10^(9) Hz

Formula for wavelength is;

Wavelength = speed of light/frequency

Speed of light = 3 × 10^(8) m/s

Thus;

Wavelength = (3 × 10^(8))/(40 × 10^(6))

Or wavelength = (3 × 10^(8))/(2.6 × 10^(9))

So,wavelength = 7.5 m or 0.12 m

This falls into the given range of 0.10 to 10.0 m.

Thus, the statement is true.

Answer:

I believe it is B, not 100% sure though

Explanation:

Answer:

A. increases

Explanation:

The relationship between air pressure (atmospheric pressure) and the density of the atmosphere is inversely proportional.

Answer:

r = 14.13 m

Explanation:

Given that,

Charge 1, q₁ = +0.0129 C

Charge 2, q₂ = -0.00707 C

The force between charges, F = 4110 N

We need to find the distance between charges. The formula for the force between charges is given by :

[tex]F=k\dfrac{q_1q_2}{r^2}[/tex]

Where

r is the distance between charges

So,

[tex]r=\sqrt{\dfrac{kq_1q_2}{F}} \\\\r=\sqrt{\dfrac{9\times 10^9\times 0.0129 \times 0.00707 }{4110 }} \\\\r=14.13\ m[/tex]

So, the distance between charges is equal to 14.13 m.

Answer:

14.13 m

Explanation:

acellus

Answer:

A black body radiator is an idealized body that absorbs all incoming electromagnetic radiation (thus the name of "black body").

A black body radiator is an object that has a lot of thermal energy, and it irradiates its thermal energy in the form of black body radiation (thermal radiation emitted by a black body).

a) Then, we could go to the trivial case of a mirror, a mirror is a poor blackbody radiator because a mirror reflects most of the incoming electromagnetic radiation, thus, a mirror is a really bad approximation for a black body, then a mirror is a poor black body radiator.

b) Any electromagnetic wave is a light wave (there exists "light" that we can not see). A black body radiator irradiates energy, and this radiation is in the form of electromagnetic waves, which are in essence, light waves.

Answer:

A black body radiator is an idealized body that absorbs all incoming electromagnetic radiation (thus the name of "black body").

A black body radiator is an object that has a lot of thermal energy, and it irradiates its thermal energy in the form of black body radiation (thermal radiation emitted by a black body).

a) Then, we could go to the trivial case of a mirror, a mirror is a poor blackbody radiator because a mirror reflects most of the incoming electromagnetic radiation, thus, a mirror is a really bad approximation for a black body, then a mirror is a poor black body radiator.

b) Any electromagnetic wave is a light wave (there exists "light" that we can not see). A black body radiator irradiates energy, and this radiation is in the form of electromagnetic waves, which are in essence, light waves.

Explanation:

Answer:

-2.2cm

Explanation:

A dentist uses a concave mirror to examine a tooth that is 1.00 cm in front of the mirror. The image of the tooth forms 10.0 cm behind the mirror. What is the mirror's radius of curvature 0.909 m.

To determine the mirror's radius of curvature, we can use the mirror formula:

1/f = 1/v - 1/u

Where:

f is the focal length of the mirror

v is the image distance (distance of the image from the mirror)

u is the object distance (distance of the object from the mirror)

In this case, the object distance (u) is 1.00 cm and the image distance (v) is -10.0 cm (since the image is formed behind the mirror, the distance is negative).

1/f = 1/(-10.0) - 1/(1.00)

Simplifying the equation:

1/f = -0.1 - 1

1/f = -1.1

Now, we can find the reciprocal of both sides of the equation:

f/1 = -1/1.1

f ≈ -0.909 m

The negative sign indicates that the mirror is concave.

Therefore, the mirror's radius of curvature is approximately 0.909 m.

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Answer:

The border is 8km above sea level.

Explanation:

We know that:

Density = 1.25 kg/m^3

Pressure = 10^5 N/m^2

g = 10m/s^2

Now, suppose that we have a virtual rectangle, such that its bases have an area of 1m^2 and the rectangle has a height equal to H.

This virtual figure has a volume V = 1m^2*H, and it is filled with air (which we know that has a density 1.25 kg/m^3)

Then the total mass inside that volume is:

M = (1.25 kg/m^3)*V = (1.25 kg/m^3)*(1m^2*H)

The weight of this mass is:

W = g*M = (10m/s^2)*(1.25 kg/m^3)*(1m^2*H)

And if we divide the weight in a given surface, let's say 1 m^2, we get the pressure per square meter, which we know is equal to  10^5 N/m^2

then:

P = 10^5 N/m^2 = (10m/s^2)*(1.25 kg/m^3)*(1m^2*H)*(1/m^2)

Whit this equation we can find the value of H.

10^5 N/m^2 = (10m/s^2)*(1.25 kg/m^3)*(1m^2*H)*(1/m^2)

10^5 N =  (10m/s^2)*(1.25 kg/m^3)*(1m^2*H)

(10^5 N)/(10 m/s^2) = (1.25 kg/m^3)*(1m^2*H)

(10^4 kg) = (1.25 kg/m^3)*(1m^2*H)

(10^4 kg)/( 1.25 kg/m^3) = 1m^2*H

8,000 m^3 = 1m^2*H

(8,000 m^3)/(1m^2) =H

8,000 m = H

And we want this answer in km, knowing that 1,000m = 1km

8,000m = 8km = H

The border is 8km above sea level.

Height of boundaries is 8.2 km

Normal density = 1.25 kg/m³

1 atm = 101325 N/m²

Height of boundaries

Pressure = Height × Density × Gravitational acceleration

101325 = Height × 1.25 × 9.8

101325 = Height × 12.25

Height of boundaries = 101325 / 12.25

Height of boundaries = 8271.42 m

Height of boundaries = 8.2 km

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Answer:

The moon does not stay at the same distance of the earth because the ortbit of the moon is slightly elliptical. If earth is not tilted at an angle of 66.5°, there will be no change in the season and the earth will have equal length of days and night.

Explanation:

mark me brainlest

When light encounters transparent materials, almost all of it passes directly through them. Glass, for example, is transparent to all visible light. ... Most of the light is either reflected by the object or absorbed and converted to thermal energy. Materials such as wood, stone, and metals are opaque to visible light.

Answer:

the average induced emf in the coil is 0.016 V.

Explanation:

Given;

diameter of the wire, d = 14.1 cm = 0.141 m

change in magnetic filed strength, dB = 0.52 T - 0.23 T = 0.29 T

change in time, dt = 0.28 s

The area of the wire is calculated as follows;

[tex]A = \frac{\pi d^2}{4} \\\\A = \frac{\pi \times (0.141)^2}{4} \\\\A = 0.0156 \ m ^2[/tex]

The induced emf is calculated as follows;

[tex]emf = \frac{dBA}{dt} \\\\emf = \frac{0.29 \times 0.0156}{0.28} \\\\emf = 0.016 \ V[/tex]

Therefore, the average induced emf in the coil is 0.016 V.

The final angular velocity of the carnival ride at a displacement of 6.3 rad is 25.2 rad/s.

The final angular velocity of the carnival ride is determined by applying third kinematic equation as shown below;

ωf = ωi + 2αθ

where;

ωf = 0 + 2(2.0) x 6.3

ωf = 25.2 rad/s

Thus, the final angular velocity of the carnival ride at a displacement of 6.3 rad is 25.2 rad/s.

​

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Answer: 5.0 rad/s

Explanation: Because that’s what khan said so try it out.

The data table for the decomposition reaction of hydrogen peroxide H₂ O₂ shows down over time as the reactant rate get used up.

What is rate, reaction and rate of reaction?

Rate- The rate of a particular chemical reaction is calculated by dividing the rate of change in a reactant's or product's concentration by the coefficient from the given balanced equation.

Reactions- They are defined as the change of a chemical substance into an innovative substance through the formation and breaking of bonds among distinct atoms.

Rate of reaction- It is defined as the ratio of the increase in product concentration per unit time to the decrease in reactant concentration per unit time. The rate of reaction varies greatly.

It can be seen that with the concentration, the rate of decomposition is also decreased. Generally, it is found that as per hour concentration and rate of decomposition decreases as well.

Therefore, (A) option is the correct answer.

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Answer:

i. Statements A and B

Explanation:

Sana nakatulong

Answer:

1992.008J

Explanation:

Answer:

Why does it take sometimes to be brighter again after eclipse? The moon looks dimmer before lunar eclipse because the moon enters into shadow of penumbra region of earth. As a result, the brightness of moon decreases and looks dimmer.

Explanation:

Answer: The moon looks dimmer before lunar eclipse because the moon enters into shadow of penumbra region of earth. As a result, the brightness of moon decreases and looks dimmer.

Explanation:

Answer:

too many

Explanation:

Answer:

the wave represents the second harmonic.

Explanation:

Given;

length of the cord, L = 64 cm

The first harmonic of a cord fixed at both ends is given as;

[tex]f_o = \frac{V}{2L}[/tex]

The wavelength of a standing wave with two antinodes is calculated as follows;

L = N---> A -----> N    +   N ----> A -----> N

Where;

N is node

A is antinode

L = N---> A -----> N    +   N ----> A -----> N =  λ/2  + λ/2

L = λ

The harmonic is calculated as;

[tex]f = \frac{V}{\lambda} \\\\f = \frac{V}{L} = 2(\frac{V}{2L} ) = 2(f_o) = 2^{nd} \ harmonic[/tex]

Therefore, the wave represents the second harmonic.

L = λ

Answer:

8m/s^2

Explanation:

hope it helps........

Explanation:

you're supposed to know the formula of acceleration which is velocity of a time then you can solve the question

Correct question is;

A 4-foot spring measures 8 feet long after a mass weighing 8 pounds is attached to it. The medium through which the mass moves offers a damping force numerically equal to √2 times the instantaneous velocity. Find the equation of motion if the mass is initially released from the equilibrium position with a downward velocity of 7 ft/s. (Use g = 32 ft/s²)

Answer:

x(t) = 7te^(-2t√2)

Explanation:

We are given;

Weight; W = 8 lbs

mass; m = W/g

g = 32 ft/s²

Thus;

m = 8/32

m = ¼ slugs

From Newton's second law we can write the equation as;

m(d²x/dt²) = -kx - β(dx/dt)

Rearranging this, we have;

(d²x/dt²) + (β/m)(dx/dt) + (k/m)x = 0

Where;

β is damping constant = √2

k is spring constant = W/s

Where s = 8ft - 4ft = 4ft

k = 8/4

k = 2

Thus,we now have;

(d²x/dt²) + (√2/(¼))(dx/dt) + (2/(¼))x = 0

>> (d²x/dt²) + (4√2)dx/dt + 8x = 0

The auxiliary equation of this is;

m² + (4√2)m + 8 = 0

Using quadratic formula, we have;

m1 = m2 = -2√2

The general solution will be gotten from;

x_t = c1•e^(mt) + c2•t•e^(mt)

Plugging in the relevant values gives;

x_t = c1•e^(mt) + c2•t•e^(mt)

At initial condition of t = 0, x_t = 0 and thus; c1 = 0

Also at initial condition of t = 0, x'(0) = 7 and thus;

Since c1 = 0, then c2 = 7

Thus,equation of motion is;

x(t) = 7te^(-2t√2)

Answer:

the length of the wire is 134.62 m.

Explanation:

Given;

resistivity of the copper wire, ρ = 2.6 x 10⁻⁸ Ωm

cross-sectional area of the wire, A  = 35 x 10⁻⁴ cm² = ( 35 x 10⁻⁴) x 10⁻⁴ m²

resistance of the wire, R = 10Ω

The length of the wire is calculated as follows;

[tex]R = \frac{\rho L}{A} \\\\L = \frac{RA}{\rho} \\\\L= \frac{10 \times (35\times 10^{-4}) \times 10^{-4}}{2.6 \times 10^{-8}} \\\\L = 134.62 \ m[/tex]

Therefore, the length of the wire is 134.62 m.

Answer:

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Explanation:

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Answer:

e. Combustion

Explanation:

In Combustion reaction, a substance reacts with oxygen from the air and resultant product is that it releases carbon dioxide and water.

Here,

2C2H6 is the substance that reacted with 7O2 (Oxygen) to release 4CO2 (Carbon Dioxide) and 6H2O (Water).

Answer:

velocity = 37.01 m/s

Explanation:

momentum = mass * velocity

61250 = 1655 * x

x = 61250 / 1655

x = 37.0090634441