"Pluto was the first dwarf planet to be discovered" is the one statement among the following choices given in the question that is true <span>about dwarf planets. The correct option among all the options that are given in the question is the first option or option "a". Pluto was classified as a planet at first but in the year 1930 it was classified as a dwarf planet.</span>
Answer:
A. Geocentric: This model is Earth Centered
. Retrograde motion is explained by epicycles
.
B. Heliocentric: This model is Sun centered. Retrograde motion is explained by the orbital speeds of planets
C. Both geocentric and heliocentric: Epicycles and deferents help explain planetary motion
. Planets move in circular orbits and with uniform motion
. The brightness of a planet increases when the planet is closest to Earth.
Explanation:
The principle of the Ptolemy's geocentric model was developed on the assumption that the center of the universe is the Earth. On the other hand, the principle of the Copernicus' heliocentric model was based on the assumption that the center of the universe is the sun. However, both models have a common ideology on uniform circular motion and epicycles.
Answer:
210
Explanation:
A ball rolls horizontally off the cliff at a speed of 30 m/s. It takes 7 seconds for the ball to hit the ground. What is the height of the cliff and the horizontal distance traveled by the ball?
S = (1/2)*9.8 m/s^2 * 7^2 = 240.1 m if the ball is very dense so air resistance, and therefore terminal velocity, can be ignored.
S = v * t = 30 m/s * 7 s = 210 m for the horizontal distance, again assuming negligible air resistance.
Impulse = change of momentum
Impulse = 45 x 6 = 270 Ns
