Orbits of the planets and centripetal acceleration

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SUMMARY

This discussion focuses on the relationship between the radius of a planet's orbit and its centripetal acceleration, specifically examining the equation arad = Crn. Participants analyze data from the solar system, including average distances from the Sun and orbital periods for planets like Mercury, Venus, Earth, and others. The goal is to determine the constants C and n by plotting ln arad against ln r, which will reveal how centripetal acceleration varies with distance from the Sun. The analysis concludes that as the distance from the Sun increases, the centripetal acceleration decreases.

PREREQUISITES
  • Understanding of centripetal acceleration and its formula arad = (4π²R)/(T²)
  • Familiarity with logarithmic functions and their properties
  • Basic knowledge of planetary orbits and Kepler's laws
  • Ability to create and interpret graphs, particularly ln transformations
NEXT STEPS
  • Calculate centripetal acceleration for each planet using the formula arad = (4π²R)/(T²)
  • Graph ln arad versus ln r to determine the constants C and n
  • Research the implications of Kepler's laws on planetary motion
  • Explore the effects of mass and size of planets on their orbital dynamics
USEFUL FOR

Astronomy students, physics enthusiasts, and educators seeking to understand the dynamics of planetary motion and centripetal acceleration in relation to distance from the Sun.

sweetchoco1
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1. The table below lists the average distance from each planet to the Sun and the
time each planet takes to make a complete orbit around the Sun (“Orbital period”).
The orbits of all of the planets are roughly circular. Your job is to determine a
relationship between the radius r of a planet’s orbit (in meters) and the centripetal
acceleration arad of the planet (in m/s2). In particular, you are to see whether these
two quantities can be related by an equation of the form

arad = Crn,

where C and n are constants. You are then to determine the values of C and
n. Based on your results, determine whether the acceleration of the planets increases,
decreases, or stays the same as the Sun-planet distance increases, and discuss
whether the size of the planet seems to affect its acceleration. Note that if you
take the natural log of the above equation, you get

ln arad = n ln r + lnC.

Thus to find the value of n, you will find it helpful to make a graph of ln arad versus
ln r. Can you see why?

Planet Average distance from Sun (106 km) Orbital period (years)
Mercury 57.9 0.241
Venus 108.2 0.615
Earth 149.6 1.000
Mars 227.9 1.88
Jupiter 778.3 11.86
Saturn 1429 29.46
Uranus 2871 84.10
Neptune 4498 164.86
Pluto 5915 248.60



2. arad=(4*pi2*R)/(T2)




3. I know how to solve for centripetal acceleration. I just don't get how to get C and n.
 
Physics news on Phys.org
From arad=(4*pi2*R)/(T2)

Find the various arad for each T.

Then you have arad = n ln r + lnC, which is in the form Y=MX+C, so what is Y and X?
 

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