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aksik [14]
3 years ago
15

In order to effectively radiate a radio signal, an antenna must be at least one-half the wavelength of transmission in length, i

.e., minimum antenna height = 1/2(λ). WITY operates at a frequency of 980.0 kHz. What is the minimum height (m) of the antenna that WITY (nostalgia radio) must have?,
Physics
1 answer:
Virty [35]3 years ago
6 0
<span>The equation that relates Wavelength & frequency of electromagnetic waves is : Velocity (c) = Wavelength (λ) * frequency (f) ------ (1) Electromagnetic wave velocity (c) = Speed of Light = 3 * 10^8 m/s From (1), Wavelength , λ = c / f λ= (3*10^8)/(980*10^3) λ = 306.12 m Minimum height of the antenna for effective transmission = λ * 0.5 = 306.12*0.5 Answer : 153 m (rounded off)</span>
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A distance of 0.002 m separates two objects of equal mass. If the gravitational force between them is
Alika [10]

Answer: 24.97 kg

Explanation:

The gravitational force between two objects of masses M1, and M2 respectively, and separated by a distance R, is:

F = G*(M1*M2)/R^2

Where G is the gravitational constant:

G = 6.67*10^-11 m^3/(kg*s^2)

In this case, we know that

R = 0.002m

F = 0.0104 N

and that M1 = M2 = M

And we want to find the value of M, then we can replace those values in the equation to get

0.0104 N = (6.67*10^-11 m^3/(kg*s^2))*(M*M)/(0.002m)^2

(0.0104 N)*(0.002m)^2/(6.67*10^-11 m^3/(kg*s^2)) = M^2

623.69 kg^2 = M^2

√(623.69 kg^2) = M = 24.97 kg

This means that the mass of each object is 24.97 kg

6 0
3 years ago
A perpetual-motion machine can never be built because it is not possible to eliminate...
bazaltina [42]
The answer is:  [C]:  "elasticity" .
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4 0
2 years ago
Read 2 more answers
A high jumper jumps 2.04 m. If the jumper has a mass of 67 kg, what is his gravitational potential energy at the highest point i
Mariulka [41]

Answer: 1339.5 joules

Explanation:

Gravitational potential energy, GPE is the energy possessed by the jumper as he moves against gravity.

Thus, GPE = Mass m x Acceleration due to gravity g x Height h

Since Mass = 67kg

g = 9.8m/s^2

h = 2.04 metres

Thus, GPE = 67kg x 9.8m/s^2 x 2.04m

GPE = 1339.5 joules

Thus, the gravitational potential energy at the highest point is 1339.5 joules

3 0
3 years ago
A drowsy cat spots a flowerpot that sails first up and then down past an open window. the pot was in view for a total of 0.49 s,
Alika [10]

For this case, let's assume that the pot spends exactly half of its time going up, and half going down, i.e. it is visible upward for 0.245 s and downward for 0.245 s. Let us take the bottom of the window to be zero on a vertical axis pointing upward. All calculations will be made in reference to this coordinate system. <span>

An initial condition has been supplied by the problem: 

s=1.80m when t=0.245s 

<span>This means that it takes the pot 0.245 seconds to travel upward 1.8m. Knowing that the gravitational acceleration acts downward constantly at 9.81m/s^2, and based on this information we can use the formula:

s=(v)(t)+(1/2)(a)(t^2) 

to solve for v, the initial velocity of the pot as it enters the cat's view through the window. Substituting and solving (note that gravitational acceleration is negative since this is opposite our coordinate orientation): 

(1.8m)=(v)(0.245s)+(1/2)(-9.81m/s^2)(0.245s)^2 

v=8.549m/s 

<span>Now we know the initial velocity of the pot right when it enters the view of the window. We know that at the apex of its flight, the pot's velocity will be v=0, and using this piece of information we can use the kinematic equation:

(v final)=(v initial)+(a)(t) 

to solve for the time it will take for the pot to reach the apex of its flight. Because (v final)=0, this equation will look like 

0=(v)+(a)(t) 

Substituting and solving for t: 

0=(8.549m/s)+(-9.81m/s^2)(t) 

t=0.8714s 

<span>Using this information and the kinematic equation we can find the total height of the pot’s flight:

s=(v)(t)+(1/2)(a)(t^2) </span></span></span></span>

s=8.549m/s (0.8714s)-0.5(9.81m/s^2)(0.8714s)^2

s=3.725m<span>

This distance is measured from the bottom of the window, and so we will need to subtract 1.80m from it to find the distance from the top of the window: 

3.725m – 1.8m=1.925m</span>

 

Answer:

<span>1.925m</span>

3 0
3 years ago
If each of the three rotor helicopter blades is 3.50 m long and has a mass of 120 kg , calculate the moment of inertia of the th
devlian [24]

Answer:

1470kgm²

Explanation:

The formula for expressing the moment of inertial is expressed as;

I = 1/3mr²

m is the mass of the body

r is the radius

Since there are three rotor blades, the moment of inertia will be;

I = 3(1/3mr²)

I = mr²

Given

m = 120kg

r = 3.50m

Required

Moment of inertia

Substitute the given values and get I

I = 120(3.50)²

I = 120(12.25)

I = 1470kgm²

Hence the moment of inertial of the three rotor blades about the axis of rotation is 1470kgm²

7 0
3 years ago
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