To determine the acceleration due to gravity by means of a conical pendulum

ExpConPenA student conducted an experiment to measure the acceleration of gravity. He used a conical pendulum. The conical pendulum is a string with a bob (weight) that revolves around an axis through its point of suspension.
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A geostationary satellite

Geostationaryjava3DsideviewA geostationary satellite is a satellite in geostationary orbit, with an orbital period the same as the Earth’s rotation period. The geostationary orbit is a circular orbit directly above the Earth’s equator.

How high above the Earth’s surface must the geostationary satellite be placed into orbit?

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If the solar system were reduced

Solar System (artist's impression) If all the linear dimensions of the solar system were reduced in some proportion, then what will be the length of Earth’s year?


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Radius of the circular path described by a proton

ProtonInMagnetFieldProtons having a kinetic energy of 20 keV are moving in a plane perpendicular to a magnetic field B = 0.05 T directed out of the plane.
Find the radius of the circular path.

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A Satellite Orbits The Moon


Image Credit: NASA Ames/Dana Berry

A satellite orbits the Moon in a circular orbit. The radius of the Moon is 1.74×10^6 m , the mass of the Moon is 7.35×10^22 kg. Calculate the speed of a satellite in a circular orbit, very near the Moon’s surface.


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The Polar Ice Cap Is Now Melting

imageAccording to NASA, the polar ice cap is now melting at the alarming rate and sea-level rise all around the Earth. This redistribution of mass will cause the Earth’s day to become

a) longer
b) shorter
c) stay the same
d) the earth will stop rotating
e) not enough information

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A question about the Moon.

Moon2The fact that the Moon always shows its same face to Earth is evidence that the Moon rotates about its axis
A. about once per day.
B. about once per week.
C. about once per month.
D. about once per year.
E. None of these, for the moon does not rotate about an axis.

Answer. Posted on Monday, December 1, 2014.