I need help with this

Wavelength = speed / frequency.

Wavelength = 3x10^8 m/s / 30 hz

Wavelength = 10 million meters

1/2 wavelength = 5 million meters

(that's about 3,100 miles)

I'm pretty sure the frequency is wrong in the question.

I think it's actually 30 kHz, not 30 Hz.

That makes the antenna about 3.1 miles long.

Answer:

v2(final)=5 m/s

Explanation:

we are going to use the conservation of momentum here

m1*v1(initial)+m2*v2(initial)=m1*v1(final)+m2v2(final)

m1=7 kg  v1(initial)=10 m/s

m2=14 kg  v2(initial)=0 m/s (bc initially it is at rest)

v1(final)= 0 m/s (m1 stops moving after the collision)

v2(final)=?

7*10+14*0=7*0+14*v2(final)

70=14v2(final)

v2(final)=70/14 m/s=5 m/s

I believe the answer is a

Answer:

12 min

Explanation:every 4 minutes is 1 mile

Answer:

6.12 m/s

Explanation:

Using the law of conservation of momentum

momentum before collision = momentum after collision

m₁v₁ + m₂v₂ = (m₁ + m₂)V    (since the train cars become attached to each other) where m₁ = mass of car 1 = 1,825 kg, m₂ = mass of car 2 = 2,645 kg, v₁ = initial velocity of car 1 = + 15.0 m/s (positive since it is moving in the positive x direction), v₂ = initial velocity of car 2 = 0 m/s (since it is initially stationary) and V = velocity of both cars after collision,

So, m₁v₁ + m₂v₂ = (m₁ + m₂)V  

m₁v₁ + m₂(0 m/s) = (m₁ + m₂)V  

m₁v₁ + 0 = (m₁ + m₂)V  

V = m₁v₁/(m₁ + m₂)

substituting the values of the other variables into the equation, we have

V = 1,825 kg × 15.0 m/s/(1,825 kg + 2,645 kg)

V = 27375 kgm/s/ 4470kg

V = 6.124 m/s

V ≅ 6.12 m/s

Answer:

A) B = 9.425 × 10^(-5) T

B) North direction

Explanation:

A) We are given;

Current in coil; I = 4.5 A

Number of turns; N = 100 turns

Radius;R = diameter/2 = 6/2 = 3 m

Formula for the magnetic field at the center of the coil is given by;

B = (μ_o•N•I)/2R

Where μ_o is a constant = 4π × 10^(-7) H/m

Thus;

B = (4π × 10^(-7) × 100 × 4.5)/(2 × 3)

B = 9.425 × 10^(-5) T

B) The direction of the force on a positive ion in water can be gotten by the application of flemmings right hand rule.

From flemmings right hand rule, we know that;

- The thumb indicates the direction of the motion of the force which is in the north direction.

- The Index finger indicates the direction of the magnetic field which is in the east direction

- The middle finger indicates the direction of magnetic field which is downwards in the west direction.

Therefore, the direction of the force as seen from flemmings right hand rule is in the north direction

Answer:

Explanation

Answer:

1) Magnesium metal/magnesium ion

2) Aluminum/aluminum ion

3)  Copper metal/copper(l) ion

Explanation:

The activity series is a series that shows the ease of reactivity of substances in an electrochemical cell.

The substances that are higher up in the series are more reactive in electrochemical cells.

Magnesium is the first element in the series that has the most negative redox potential  then followed aluminium.

Hence, according to Nernst,

1) Magnesium metal/magnesium ion

2) Aluminum/aluminum ion

3)  Copper metal/copper(l) ion

Answer:

a. i. 3.43 m/s ii. 2.8 m/s

b. The thin-walled cylinder

Explanation:

a. Find translational speed of each cylinder upon reaching the bottom

The potential energy change of each mass = total kinetic energy gain = translational kinetic energy + rotational kinetic energy

So, mgh = 1/2mv² + 1/2Iω² where m = mass of object = 2.0 kg, g =acceleration due to gravity = 9.8 m/s², h = height of incline = 1.2 m, v = translational velocity of object, I = moment of inertia of object and ω = angular speed = v/r where r = radius of object.

i. translational speed of thin-walled cylinder upon reaching the bottom

So, For the thin-walled cylinder, I = mr², we find its translational velocity, v

So, mgh = 1/2mv² + 1/2Iω²

mgh = 1/2mv² + 1/2(mr²)(v/r)²  

mgh = 1/2mv² + 1/2mv²

mgh = mv²

v² = gh

v = √gh

v = √(9.8 m/s² × 1.2 m)

v = √(11.76 m²/s²)

v = 3.43 m/s

ii. translational speed of solid cylinder upon reaching the bottom

So, For the solid cylinder, I = mr²/2, we find its translational velocity, v'

So, mgh = 1/2mv'² + 1/2Iω²

mgh = 1/2mv² + 1/2(mr²/2)(v'/r)²  

mgh = 1/2mv'² + mv'²

mgh = 3mv'²/2

v'² = 2gh/3

v' = √(2gh/3)

v' = √(2 × 9.8 m/s² × 1.2 m/3)

v' = √(23.52 m²/s²/3)

v' = √(7.84 m²/s²)

v' = 2.8 m/s

b. Determine which cylinder has the greatest translational speed upon reaching the bottom.

Since v = 3.43 m/s > v'= 2.8 m/s,

the thin-walled cylinder has the greatest translational speed upon reaching the bottom.

Answer:

- the expected value is 8

- the standard deviation is 2.8284

Explanation:

Given the data in the question;

The model N(t), the number of planets found up to time t, as a poisson process,

∴ N(t) has distribution of poisson distribution with parameter (λt)

so

the mean is;

λ = 1 every month = 1/3 per month

E[N(t)] = λt

E[N(t)] = (1/3)(24)

E[N(t)] = 8

Therefore, the expected value is 8

For poisson process, Variance and mean are the same,

Var[N(t)] = Var[N(24)]

Var[N(t)] = E[N(24)]

Var[N(t)] = 8

so the standard deviation will be;

σ[N(24)] = √(Var[N(t)] )

σ[N(24)] = √(8 )

σ[N(24)] = 2.8284

Therefore, the standard deviation is 2.8284

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

Answer:

Initial velocity u = 60 ft/s

Explanation:

Given:

Deceleration a = -36 ft/s²

Distance covered s =50ft

Final  velocity v = 0 ft/s

Find:

Initial velocity u

Computation:

Using third equation of motion;

v² = u² + 2as

0² = u² + 2(-36)(50)

0 = u² - 3600

u² = 3600

u = 60 ft/s

Initial velocity u = 60 ft/s

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:

Please I do not understand the instructions given at the end of the question

Answer: 0.516 ft/s

Explanation:

Given

Length of ladder L=20 ft

The speed at which the ladder moving away is v=2 ft/s

after 1 sec, the ladder is 5 ft away from the wall

So, the other end of the ladder is at

[tex]\Rightarrow y=\sqrt{20^2-5^2}=19.36\ ft[/tex]

Also, at any instant t

[tex]\Rightarrow l^2=x^2+y^2[/tex]

differentiate w.r.t.

[tex]\Rightarrow 0=2xv+2yv_y\\\\\Rightarrow v_y=-\dfrac{x}{y}\times v\\\\\Rightarrow v_y=-\dfrac{5}{19.36}\times 2=0.516\ ft/s[/tex]

Answer:

The equation says that due to variation in temperature is

delt T = .59 m/s / C = 16 C * .59 m/s = 9.44 m/s

So v = 332 m/s + 9.44 m/s = 341 m/s (to three significant figures)

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:

Cytoplasm

Explanation:

Answer: After fusing helium in its core to carbon, the Sun will begin to collapse again, evolving into a compact white dwarf star after ejecting its outer atmosphere as a planetary nebula. The predicted final mass is 54.1% of the present value, most likely consisting primarily of carbon and oxygen.

Answer: the Sun will begin to collapse

Explanation: "After fusing helium in its core to carbon, the Sun will begin to collapse again, evolving into a compact white dwarf star after ejecting its outer atmosphere as a planetary nebula. The predicted final mass is 54.1% of the present value, most likely consisting primarily of carbon and oxygen."

Answer:

The current in the new circuit is 0

Explanation:

A diode is an electronic component that allows the electric current to go only in one direction. If in the first case the current was 255 mA, and the battery was changed ( change in polarity ) no current will flow through the circuit. That change is similar or equivalent to change the diode to the no pass position

Answer:

kilogram

In the International System of Units (SI), the kilogram is the basic unit of mass, and the newton is the basic unit of force. The non-SI kilogram-force is also a unit of force typically used in the measure of weight.

Answer:

The average speed throughout the journey was 76.36 kilometers per hour.

Explanation:

Given that a car driver spends 3hrs driving at an average speed of 80km / hr, stops for 30 minutes to have some rest, and then drives at an average speed of 90km / hr for 2 hours, to determine the average speed during the whole journey the following calculation must be performed:

80 km / h x 3 = 240 km

90 km / h x 2 = 180 km

240 + 180 = 420 km

3 + 2 + 0.5 = 5.5 hours

420 / 5.5 = 76.36

Thus, the average speed throughout the journey was 76.36 kilometers per hour.

Answer:

well in the pot there is conventional heat, the pot itself is giving off conductable heat, and the radiational heat is coming from the stove.

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:

A main sequence star is powered by fusion of hydrogen into helium in its core

Explanation:

Answer:

Explanation:

Time period of rotation

T = 2πR/ V where R is radius of orbit and V is orbital velocity

Orbital velocity V = √ ( GM/R ) , m is mass of the earth .

T = 2πR √R / GM

T² = 4π²R³ / GM

Putting the values

( 126 x 60 )² = 4 x 3.14² x R³ / 6.67 x 10⁻¹¹ x 5.97 x 10²⁴

57.15 x 10⁶ = 39.44 x R³ / 39.82 x 10¹³

R³ = 577 X 10¹⁸

R = 8.325 x 10⁶ m

= 8325 km

Radius of earth = 6400 km

height of satellite = 8325- 6400 = 1925 km .

Answer:

[tex]24.9\ \text{m/s}[/tex]

[tex]206.7\ \text{m}[/tex]

Explanation:

m = Mass of skydiver = 80 kg

[tex]x_1[/tex] = Height for which the parachute is closed = 1000-200 = 800 m

[tex]x_2[/tex] = Height for which the parachute is open = 200 m

[tex]f_1[/tex] = Resistive force when parachute is closed = 50 N

[tex]f_2[/tex] = Resistive force when parachute is open = 3600 N

v = Velocity of skydiver on the ground

g = Acceleration due to gravity = [tex]9.81\ \text{m/s}^2[/tex]

h = Height from which the skydiver jumps = 1000 m

The energy balance of the system will be

[tex]mgh-f_1x_1-f_2x_2=\dfrac{1}{2}mv^2\\\Rightarrow 80\times 9.81\times 1000-50\times 800-3600\times 200=\dfrac{1}{2}\times 80\times v^2\\\Rightarrow v=\sqrt{\dfrac{2(80\times 9.81\times 1000-50\times 800-3600\times 200)}{80}}\\\Rightarrow v=24.9\ \text{m/s}[/tex]

The velocity fo the skydiver when he lands will be [tex]24.9\ \text{m/s}[/tex]

x = Height where the person opens the parachute

v = 5 m/s

[tex]mgh-f_1x_1-f_2x_2=\dfrac{1}{2}mv^2\\\Rightarrow 80\times 9.81\times 1000-50\times (1000-x)-3600\times x=\dfrac{1}{2}\times 80\times 5^2\\\Rightarrow 80\times 9.81\times 1000-50000+50x-3600x=\dfrac{1}{2}\times 80\times 5^2\\\Rightarrow x=\dfrac{80\times 9.81\times 1000-50000-\dfrac{1}{2}\times 80\times 5^2}{3550}\\\Rightarrow x=206.7\ \text{m}[/tex]

The height at which the parachute is to be opened is [tex]206.7\ \text{m}[/tex]

Answer:

The acceleration of the football is greatest

Explanation:

The more mass the more acceleration