1.A certain spacecraft is 3.3 AU (Astronomical Units) from Earth. How long in seconds does it take for a signal to reach the Earth after it is transmitted from the spacecraft? Hint: An AU is about 149.9 Million Km, and light moves at 299,800 Km/s. {Indicate your answer to the nearest whole second).
2.IF a particular galaxys has a total mass of 10 to the 52 grams and the average star in that galaxy has a mass of 10 to the 38 grams, approximately how many stars are there in that galaxy? Give your answer to the nearest whole power of 10 by entering the exponent only.
3.A particular spiral galaxy can be approximated by a thin disk-like volume 88 Thousand Light Years in radius and 5 Hundred Light Years thick. If this Galaxy contains 1,050 Billion stars, estimate the average distance between the stars in this galaxy. Hint: calculate the average volume per star in cubic Light Years, and then estimate the approximate linear dimension across such a volume.
4.Given that the acceleration of gravity at the Earth's surface is about 980 cm per sec per sec, the centripetal acceleration [v squared over r] of an artificial satellite in a circular orbit with a radius 2.7 times that of the Earth's radius would be about _____ cm per sec per sec. (Hint: F = m a, and the force of gravity gets weaker as the square of the distance, so how much weaker is gravity at 2.7 times the Earth's Radius than it is at the surface of the Earth?)
Update: 5.If a certain force accelerates an object of mass 29 Kg at 59 m/s/s, what acceleration in m/s/s would the same force produce on another object of mass 29? Enter answer to at least one decimal place to the right of the decimal point.
6.If the distance between the Earth and the Sun were increased by a factor of 5.26, by what factor would the strength of the force between them change? [Hint: Use Newton's Law of Universal Gravitation, and give your answer to 2 decimal places only]
Update 2: 7.The term "void ratio" means the ratio of the volume of empty space to volume of occupied space. It is a measure of how empty a volume is. Within stellar systems, the average separation between planets is roughly 10 to the 15 cm and the average planetary radius is typically 10 to the 15 cm. The void ratio for this stellar system is roughly 10 to what power:
Update 3: 7.The term "void ratio" means the ratio of the volume of empty space to volume of occupied space. It is a measure of how empty a volume is. Within stellar systems, the average separation between planets is roughly 10 to the 15 cm and the average planetary radius is typically 10 to the 15 cm. The void ratio for this stellar system is roughly 10 to what power
1 answer