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alukav5142 [94]
2 years ago
15

A space expedition discovers a planetary system consisting of a massive star and several spherical planets. The planets all have

the same uniform mass density. The orbit of each planet is circular.
In the observed planetary system, Planet A orbits the central star at the distance of 2R and takes T hours to complete one revolution around the star. Planet B orbits the central star at the distance of R. Which of the following expressions is correct for the number of hours it takes Planet B to complete one revolution around the star?

a. 1/â8T
b. 1/2T
c. 1/3â4T
d. 2T
e. â8T
Physics
1 answer:
Juliette [100K]2 years ago
7 0

Answer:

T/√8

Explanation:

From Kepler's law, T² ∝ R³ where T = period of planet and R = radius of planet.

For planet A, period = T and radius = 2R.

For planet B, period = T' and radius = R.

So, T²/R³ = k

So, T²/(2R)³ = T'²/R³

T'² = T²R³/(2R)³

T'² = T²/8

T' = T/√8

So, the number of hours it takes Planet B to complete one revolution around the star is T/√8

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Cars A and B are racing each other along the same straight road in the following manner: Car A has a head start and is a distanc
4vir4ik [10]

The question is incomplete. Here is the complete question.

Cars A nad B are racing each other along the same straight road in the following manner: Car A has a head start and is a distance D_{A} beyond the starting line at t = 0. The starting line is at x = 0. Car A travels at a constant speed v_{A}. Car B starts at the starting line but has a better engine than Car A and thus Car B travels at a constant speed v_{B}, which is greater than v_{A}.

Part A: How long after Car B started the race will Car B catch up with Car A? Express the time in terms of given quantities.

Part B: How far from Car B's starting line will the cars be when Car B passes Car A? Express your answer in terms of known quantities.

Answer: Part A: t=\frac{D_{A}}{v_{B}-v_{A}}

              Part B: x_{B}=\frac{v_{B}D_{A}}{v_{B}-v_{A}}

Explanation: First, let's write an equation of motion for each car.

Both cars travels with constant speed. So, they are an uniform rectilinear motion and its position equation is of the form:

x=x_{0}+vt

where

x_{0} is initial position

v is velocity

t is time

Car A started the race at a distance. So at t = 0, initial position is D_{A}.

The equation will be:

x_{A}=D_{A}+v_{A}t

Car B started at the starting line. So, its equation is

x_{B}=v_{B}t

Part A: When they meet, both car are at "the same position":

D_{A}+v_{A}t=v_{B}t

v_{B}t-v_{A}t=D_{A}

t(v_{B}-v_{A})=D_{A}

t=\frac{D_{A}}{v_{B}-v_{A}}

Car B meet with Car A after t=\frac{D_{A}}{v_{B}-v_{A}} units of time.

Part B: With the meeting time, we can determine the position they will be:

x_{B}=v_{B}(\frac{D_{A}}{v_{B}-v_{A}} )

x_{B}=\frac{v_{B}D_{A}}{v_{B}-v_{A}}

Since Car B started at the starting line, the distance Car B will be when it passes Car A is x_{B}=\frac{v_{B}D_{A}}{v_{B}-v_{A}} units of distance.

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2 years ago
What are the factors that affect the resistance of a wire?
777dan777 [17]

1) Length of the wire.

2) Thickness of the wire.

3) Temperature.

4) Type of metal.

Hope this helps!

-Payshence

6 0
3 years ago
Identifying What are five things
g100num [7]

Answer:

1. Naturally occuring

2. Solid

3. Inorganic

4. Crystalline

5. Specific Chemical Compostion

Explanation:

Minerals are inorganic, crystalline solids that occur during biogeochemical processes in nature like in cooled lava or evaporated sea water. Minerals are not rocks, but are actually the components that make up rocks. Though they vary in color and shape, each mineral has a distinct chemical composition.

1. Minerals are formed by natural geological processes. Most minerals form from molten lava, sea evaporation or hot liquids in caves or cracks. Laboratory-generated minerals like synthetic gems made for commercial purposes are not considered actual minerals.

2. Though minerals vary in shape, color, luster (the way a mineral reflects light) and hardness, all minerals are a solid at a given temperature. If a substance is not in its solid state, it is not currently a mineral. For example, ice is a mineral, but liquid water is not. The Mohr scale, rates a minerals hardness from one to 10, 10 being the hardest. Diamond is the hardest mineral. Talc is a very soft mineral with a Mohr rating of one.

3. Minerals are wholly inanimate, inorganic compounds. But there are exceptions to this qualifier. There are rare organic substances with definitive chemical compositions that are labeled as “organic minerals." The most famous of this oxymoronic exception is whewellite. Whewellite is a component of kidney stones and coal deposits.

4. Most minerals will grow into a crystal shape, space permitting. Mineral deposits are often small because there is usually a variety of minerals in the same vicinity competing for the same room to grow. A mineral’s crystalline structure determines its hardness, cleavage (how it breaks) and color. There are six different crystal shapes: cubic, tetragonal, orthohombic, hexagonal, monoclinic and triclinic.

5. A mineral is defined by its chemical composition. A rock, on the other hand, does not have a specific chemical composition because it is a composite of a variety of minerals. Minerals are classified based on their anionic group. The major mineral groups are native elements, sulfides, sulfosalts, oxides and hydroxides, halides, carbonates, nitrates, borates, sulfates, phosphates and silicates. Silica is abundant in the Earth’s crust, so silicates are the most common group of mineral.

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2 years ago
A bell rings at a frequency of 75hz on a warm 25 degree evening. calculate the...
allochka39001 [22]

Answer:

Explanation:

We need 2 different equations for this problem: first the velocity of sound equation, then the frequency of the sound equation.

The velocity of sound is found in:

v = 331.5 + .606T

We need to find that first in order to fill it into the frequency equation which is

f=\frac{v}{\lambda} where v is the velocity we will find the part a, f is frequency and lambda is the wavelength. Starting with the velocity of the sound:

v = 331.5 + .606(25) and

v = 331.5 + 15 and rounding correctly using the rules for sig fig when adding:

v = 347 m/s

Filling that into the frequency equation:

75=\frac{347}{\lambda} and

\lambda=\frac{347}{75} so

\lambda=4.6m

7 0
2 years ago
What is the forms of energy given below.
Damm [24]

Answer:

Lightening of the table lamp

Explanation:

Energy has a different form of energy. In physics, the capacity of the form of energy is work. The energy can exist in the form of thermal, potential, kinetic, chemical and electrical, and nuclear. There are other forms of energy such as work and heat.

The energy is designated according to the nature of the objects. So that when heat transferred it has been changed into thermal. All the forms of energy are related to the motion of an object. Energy can neither destroyed or created.

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