A car with a mass of 650 kg is moving with a speed of 20m/s. Calculate the kinetic energy of the car?

What's the diameter of a dish antenna that will receive 10−20W of power from Voyager at this time? Assume that the radio transmi

Murrr4er [49]

Complete Question:

The Voyager 1 spacecraft is now beyond the outer reaches of our solar system, but earthbound scientists still receive data from the spacecraft s 20-W radio transmitter. Voyager is expected to continue transmitting until about 2025, when it will be some 25 billion km from Earth.

What s the diameter of a dish antenna that will receive 10−20W of power from Voyager at this time? Assume that the radio transmitter on Voyager transmits equally in all directions(isotropically). In fact, the antenna on Voyager focuses the signal in a beam aimed at the earth, so this problem over-estimates the size of the receiving dish needed.

Answer:

d = 2,236 m.

Explanation:

The received power on Earth, can be calculated as the product of the intensity (or power density) times the area that intercepts the power radiated.

As we assume that the transmitter antenna is ominidirectional, power is spreading out over a sphere with a radius equal to the distance to the source.

So, we can get the power density as follows:

I = P /A = P / 4*π*r², where P = 20 W, and r= 25 billion km = 25*10¹² m.

⇒ I = 20 W / 4*π* (25*10¹²)² m²

The received power, is just the product of this value times the area of the receiver antenna, which we assumed be a circle of diameter d:

Pr = I. Ar =( 20W / 4*π*(25*10¹²)² m²) * π * (d²/4) = 10⁻²⁰ W

Simplifying common terms, we can solve for d:

d= √(16*(25)²*10⁴/20) = 2,236 m.

3 0

3 years ago

If the mass of a material is 42 grams and the volume of the material is 15 cm^3, what would the density of the material be?

Fantom [35]

Density = mass / volume

Density = 42g / 15cm^3

Density = 2.8g/cm^3

3 0

4 years ago

A particle, whose acceleration is constant, is moving in the negative x direction at a speed of 4.91 m/s, and 12.9 s later the p

Zinaida [17]

Answer:

The particle’s velocity is -16.9 m/s.

Explanation:

Given that,

Initial velocity of particle in negative x direction= 4.91 m/s

Time = 12.9 s

Final velocity of particle in positive x direction= 7.12 m/s

Before 12.4 sec,

Velocity of particle in negative x direction= 5.32 m/s

We need to calculate the acceleration

Using equation of motion

$v = u+at$

$a=\dfrac{v-u}{t}$

Where, v = final velocity

u = initial velocity

t = time

Put the value into the equation

$a=\dfrac{7.12-(-4.91)}{12.9}$

$a=0.933\ m/s^2$

We need to calculate the initial speed of the particle

Using equation of motion again

$v=u+at$

$u=v-at$

Put the value into the formula

$u=-5.321-0.933\times12.4$

$u=-16.9\ m/s$

Hence, The particle’s velocity is -16.9 m/s.

4 0

3 years ago

Difference between electrolytes and nonelectrolytes.

Trava [24]

Answer:

Electrolytes are salts or molecules that ionize completely in solution. As a result, electrolyte solutions readily conduct electricity. Nonelectrolytes do not dissociate into ions in solution; nonelectrolyte solutions do not, therefore, conduct electricity

Explanation:

8 0

2 years ago

Read 2 more answers

describes how the color and texture of a surface affect absorption and reflection of solar radiation?

Wewaii [24]

Most of the radiation, however, is absorbed by the earth's surface. ... Every surface on earth absorbs and reflects energy at varying degrees, based on its color and texture. Dark-colored objects absorb more visible radiation; light-colored objects reflect more visible radiation.

3 0

3 years ago