During the 28-day lunar cycle, the positions of the Sun,

Estimate the number of dollar bills (15.5 cm wide), placed end to end, that it would take to circle the Earth (radius = 6.40 × 1

marishachu [46]

Answer:

#_bills = 2.59 10⁸ Bills

Explanation:

For this exercise we must calculate the length of the Earth's circle

L = 2π r

Let's reduce to the SI system

r = 6.40 10³ km (1000m / 1km) = 6.40 10⁶ m

d = 15.5 cm (1m / 100cm) = 0.155 m

L = 2π 6.40 10⁶

L = 40.21 10⁶ m

now we can use a direct rule of proportions (rule of three). If 1 bill has d = 0.155, how much bill will have L

#_bills = 1 L / d

#_bills = 1 40.21 10⁶6 / 0.155

#_bills = 2.59 10⁸ Bills

the total number of bills is 2.6 10⁸ bills

3 0

3 years ago

The mass of a star can be determined by studying ___.

Citrus2011 [14]

Answer: C. Binary star systems

Let’s see your options:

a) The color of the star: the color is not used in calculating the mass of a star, because it has no relation to it. Think about a red supergiant and a red dwarf: they have the same color, but they are completely different stars, with respectively a big and a small mass.

b) Kepler’s laws: these laws can be applied in what is called the “approximation of 1 body”, which means that is assumed that one body has a much bigger mass than the other and can be considered at rest. This is the case of a star-planet system and the mass that can be calculated is that of the planet.

c) Binary star systems: these are the only cases in which is possible the direct measure of the mass of the stars. Binary systems are classified as follows:
- Visual binaries: each star can be resolved and the motion around the center of mass can be measured.
- Astrometric binaries: only one star is visible, but the presence of the companion can be inferred by the movement of the first star around the system’s center of mass.
- Eclipse binaries: the two stars are not resolved (separated), but the luminosity varies periodically when one star eclipses the other.
- Spectroscopic binaries: the two stars are not resolved, but their spectrum reveals that they are a binary system.
In all these cases we have a “two-body problem” that can be solved by changing system of reference: the motion of bodies 1 and 2 is equivalent to the motion of a body of mass equal to the system’s reduced mass $\mu = \frac{M_{1} \cdot M_{2}}{M_{1} + M_{2}}$ moving in the potential generated by the total mass (M1 + M2) considered at rest. Hence, we can determine the masses of the two stars.

4 0

3 years ago

Read 2 more answers

A constant magnetic field of 0.50 T is applied to a rectangular loop of area 3.0 × 10-3 m2. If the area of this loop changes fro

Nonamiya [84]

Answer:

e= 0.440 mV(millivolt)

Explanation:

Given Magnetic field B= 0.50T

$A_{1}=3\times10^{-3}$

$A_{2}=1.6\times10^{-3}\\$

Δt= 1.6sec

$induced emf e=\frac{\mathrm{d} \phi }{\mathrm{d} t}$

⇒ $e=B\frac{\mathrm{d} A}{\mathrm{d} t}$

$e=0.50\times\frac{3\times10^{-3}-1.6\times10^{-3}}{1.6}$

$e=0.440\times10^{-3} volt$

e= 0.440 mV(millivolt)

8 0

3 years ago

Jenna made an electric circuit as seen in the picture. She placed a thermometer near her light bulb. After the light bulb was tu

lisov135 [29]

The thermometer had most likely gotten a very high number on it from the heat of the light bulb. The longer he light bulb was on, the higher the number went on the thermometer.

8 0

3 years ago

Read 2 more answers

X

Gekata [30.6K]

Answer: is option C: Prolonged periods of cooling and warming.

Explanation:

In the history of Earth, climate varies time to time. At times, the Earth's atmosphere was much hotter and humid as compare to the present time, but similarly it has been noticed that climate also has been much colder than he present time, whereas the number of glaciers covers much of the Earth's surface. There are two kinds of periods in which we further classified Earth's climate namely, Glacial period, and Inter-glacial periods. It has been noticed that the average global temperature of Earth during glacial periods was around 5.5°C or 10°F, which is less than Earth's present climate. On the other hand, during inter-glacial periods Earth's temperature was about 1.1°C or 2.0°F, which is again higher as compared to current temperature. Over the past 900,000 years, Earth's temperature varied less than 5°C. Scientist believe by looking at the Earth's climate history, that glaciers will proceed again in formation, but it will take thousands of years.

8 0

3 years ago