I need help with this

Answer:

I think the answer is B, keeps Earth in a spherical shape

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.

Explanation:

mass=force*acceleration

mass=3000*10

mass=30,000

The mass of the bodies in the elevator is 400 kg.

The acceleration of the elevator is 2.5 m/s².

Acceleration is rate of change of velocity with time. Due to having both direction and magnitude, it is a vector quantity. Si unit of acceleration is meter/second² (m/s²).

Given parameters:

Mass of the elevator: M = 250 kg.

Mass of two persons: m₁ = 50 kg and m₂ = 100 kg.

Force exerted by the motor: F = 3000N.

g = 10 m/s².

Let, the acceleration of the  elevator = a.

the mass of the bodies in the elevator :m= 250 kg. + 50 kg +100 kg. = 400 kg.

Now, F = mg - ma

⇒ 3000 = 400×10 - 400a

⇒ a = 1000/400 = 2.5 m/s²

Hence, the acceleration of the elevator is 2.5 m/s².

Learn more about acceleration here:

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Answer:

12 min

Explanation:every 4 minutes is 1 mile

Answer:

B i think

Explanation:

...

Answer:

500km per hour

Explanation:

if in 2 hours the airplane flies 1000 km then 1000 divided by 2 is 500km per hour.

Answer:

a) The angular acceleration is 1.875 radians per square second.

b) The time taken by the disk to reach the final angular speed is 8 seconds.

Explanation:

a) Let suppose that the disk accelerates uniformly, given that initial and final angular speed ([tex]\omega_{o}[/tex], [tex]\omega_{f}[/tex]), in radians per second, and change in angular position ([tex]\Delta \theta[/tex]), in radians, are known. The angular acceleration ([tex]\alpha[/tex]), in radians per square second, are found by using this expression:

[tex]\alpha = \frac{\omega_{f}^{2}-\omega_{o}^{2}}{2\cdot \Delta \theta}[/tex] (1)

If we know that [tex]\omega_{o} = 0\,\frac{rad}{s}[/tex], [tex]\omega_{f} = 15\,\frac{rad}{s}[/tex] and [tex]\Delta \theta = 60\,rad[/tex], then the angular acceleration of the disk is:

[tex]\alpha = \frac{\omega_{f}^{2}-\omega_{o}^{2}}{2\cdot \Delta \theta}[/tex]

[tex]\alpha = 1.875\,\frac{rad}{s^{2}}[/tex]

The angular acceleration is 1.875 radians per square second.

b) The time taken by the disk to reach the final angular velocity is determined by the following kinematic formula:

[tex]t = \frac{\omega_{f}-\omega_{o}}{\alpha}[/tex] (2)

Where [tex]t[/tex] is the time, in seconds.

If we know that [tex]\omega_{o} = 0\,\frac{rad}{s}[/tex], [tex]\omega_{f} = 15\,\frac{rad}{s}[/tex] and [tex]\alpha = 1.875\,\frac{rad}{s^{2}}[/tex], then the time taken by the disk is:

[tex]t = \frac{\omega_{f}-\omega_{o}}{\alpha}[/tex]

[tex]t = 8\,s[/tex]

The time taken by the disk to reach the final angular speed is 8 seconds.

Answer:

150 J

Explanation:

If there is not any dissipative force in the system, the mass and the spring will oscillate eternally., but of course, we assume this is a theoretical situation. The conservation of energy in a system implies that the sum of the potential energy plus kinetic energy remains constant, therefore if in the initial point the mass has 200 J (potential energy) and is at rest ( kinetic energy = 0) the overall energy at the beginning is 200 J. At any point of the oscillation if the potential energy is 50 J the kinetic energy must be 150 J.

Answer:

Option C

Explanation:

Options for the question are as follows -

A. At a faucet close to entrance valve

B. At a faucet away from the entrance valve

C. It will be the same at all faucets

D. There will be no increase in the pressure at the faucets

Solution -

The static force will be the same at all faucets and also the area of the faucets be same.

Thus, the pressure created at all faucets will be the same.

Thus, option C is correct

Answer:

The energy goes from the ground state to the excited states above it.

Answer:

  L₀ = L_f ,  K_f < K₀

Explanation:

For this exercise we start as the angular momentum, with the friction force they are negligible and if we define the system as formed by the disk and the clay sphere, the forces during the collision are internal and therefore the angular momentum is conserved.

This means that the angular momentum before and after the collision changes.

Initial instant. Before the crash

        L₀ = I₀ w₀

Final moment. Right after the crash

        L_f = (I₀ + mr²) w

we treat the clay sphere as a point particle

how the angular momentum is conserved

       L₀ = L_f

       I₀ w₀ = (I₀ + mr²) w

       w = [tex]\frac{I_o}{I_o + m r^2}[/tex]   w₀

having the angular velocities we can calculate the kinetic energy

starting point. Before the crash

        K₀ = ½ I₀ w₀²

final point. After the crash

        K_f = ½ (I₀ + mr²) w²

sustitute

        K_f = ½ (I₀ + mr²)  ( [tex]\frac{I_o}{I_o + m r^2}[/tex]   w₀)²

        Kf = ½  [tex]\frac{I_o^2}{ I_o + m r^2}[/tex]   w₀²

we look for the relationship between the kinetic energy

        [tex]\frac{K_f}{K_o}[/tex]=   [tex]\frac{I_o}{I_o + m r^2}[/tex]

       [tex]\frac{K_f}{K_o } < 1[/tex]

      K_f < K₀          

we see that the kinetic energy is not constant in the process, this implies that part of the energy is transformed into potential energy during the collision

Answer:

[tex]f=4.70\times 10^{14}\ Hz[/tex]

Explanation:

Given that,

The wavelength of light, [tex]\lambda=6.38\times 10^{-7}\ m[/tex]

We need to find the frequency of the light. We know that,

[tex]c=f\lambda\\\\f=\dfrac{c}{\lambda}\\\\f=\dfrac{3\times 10^8}{6.38\times 10^{-7}}\\\\f=4.70\times 10^{14}\ Hz[/tex]

So, the required frequency of light is equal to [tex]4.70\times 10^{14}\ Hz[/tex].

Answer: C. Stored energy

Answer:

You can use work to add kinetic energy to a system or to increase potential energy in the system.

Explanation:

Potential energy stored in any system can be released as kinetic energy. Kinetic energy can be transformed to do work or to increase potential energy.

hope this helped

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:

air pressure

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Answer:

a) y = 127.6 m, b) 11.9s,  c)  v = 103.6  m / s, θ’= 326.7º

Explanation:

This is a missile throwing exercise

let's start by breaking down the initial velocity

         sin 30 = [tex]\frac{v_{oy} }{v_o}[/tex]

         cos 30 = v₀ₓ / v₀

         v_{oy} = v₀ go sin 30

         v₀ₓ = v₀ cos 30

         v_{oy} = 100 sin 30 = 50 m / s

         v₀ₓ = 100 cos 30 = 86.6 m / s

a) the maximum height is requested.

At this point the vertical velocity is zero (v_y = 0)

         v_y² = [tex]v_{oy}^2[/tex] - 2 g y

         0 = v_{oy}^2 - 2g y

         y = [tex]\frac{v_{oy}^2 }{2g}[/tex]

         y = 50² / (2  9.8)

         y = 127.6 m

b) Flight time

this is the time it takes to reach the ground, the reference system for this movement is taken on the ground this is a height of y = 0 m and the body is at an initial height of i = 100m

         y = y₀ + v₀ t - ½ g t²

       0 = 100 + 50 t - ½ 9.8 t²

we solve the quadratic equation

        4.9 t² - 50 t - 100 = 0

         t = [tex]\frac{50 \pm \sqrt{50^2 + 4 \ 4.9 \ 100} }{2 \ 4.9}[/tex]

         t = [tex]\frac{50 \ \pm \ 66.8}{9.8}[/tex]

         t₁ = 11.9 s

         t₂ = -8.4 s

flight time is 11.9s

c) The time 1 s before hitting the ground is

        t1 = 11.9 -1

        t1 = 10.9 s

let's find the vertical speed

       v_y =[tex]v_{oy}[/tex] - g t

       v_y = 50 - 9.8 10.9

       v_y = -56.8 m / s

the negative sign indicates that the direction of the velocity is downward.

On the x-axis there is no acceleration therefore the speed is constant.

Let's use the Pythagorean theorem

        v = [tex]\sqrt{v_x^2+v_y^2}[/tex]

        v = [tex]\sqrt { 86.6^2 + 56.8^2}[/tex]

        v = 103.6  m / s

let's use trigonometry

        tan θ = [tex]\frac{v_y}{v_x}[/tex]

        θ = tan⁻¹  \frac{v_y}{v_x}

        θ = tan⁻¹  (-56.8 / 86.60)

        θ = -33.3º

the negative sign indicates that it is measured clockwise from the x-axis

for a counterclockwise measurement

          θ’= 360 - θ

          θ' = 360 - 33.3

          θ’= 326.7º

Answer:

D. The Light Is Refracted

Explanation:

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Answer:

Distance travel by go-cart = 500 meter

Explanation:

Given:

Speed of go cart = 25 m/s

Time travel = 20 seconds

Find:

Distance travel by go-cart

Computation:

Distance = Speed x time

Distance travel by go-cart = Speed of go cart x Time travel

Distance travel by go-cart = 25 x 20

Distance travel by go-cart = 500 meter

Answer:

question #1 is A

Question #2 is C

Explanation:

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:

False

Explanation:

The Sun rotates in this same, right-hand-rule direction. All planetary orbits lie in nearly the same plane. All planetary orbits are nearly circular (eccentricity near zero).

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