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# -The accepted value of the radius of the Earth is 6.3781 ×

-The accepted value of the radius of the Earth is 6.3781 × 106 m. Compute the percent error between your result of R and the accepted value. Show your work below. -Rays from the Sun could strike the Earth with a different angle limited by your calculation above. Is the assumption of parallel light from the Sun a good approximation—considering the angles you are working with—to find the curvature of the Earth? Why or why not? -The average distance between Earth and the Sun is 1 AU = 1.49 × 108 km. If the Earth has a circular orbit with the Sun at the middle of the circle, what is the circumference of Earth’s orbit in km? Show your work and report your answer with 3 significant digits.

## 246.The REQUIRED condition for the angular momentum of an object to be conserved (i.e.,to not change) is thatA)the speed of

246.The REQUIRED condition for the angular momentum of an object to be conserved (i.e.,to not change) is thatA)the speed of the object does not change.B)the object is not acted on by an internal torque (caused, for example, by the muscles in a skater’s arms).C)the object is not acted on by an outside torque.D)the size of the object does not change.

## 267.In the years after Newton published his laws of motion, it was found that the observed positions of the planet

267.In the years after Newton published his laws of motion, it was found that the observed positions of the planet Uranus did not match the predictions of Newton’s theory. The reason for this turned out to beA)the perturbing effects of Jupiter and Saturn, whose masses at that time were not accurately known.B)the perturbing effect of Neptune, which at that time had not yet been discovered.C)the perturbing effect of Pluto, which at that time had not yet been discovered.D)the weakening of gravity with increasing distance from the Sun.

## 1.The temperature fluctuations in the Cosmic Microwave Background are due to quantum mechanical fluctuations. T/F

Question 1.The temperature fluctuations in the Cosmic Microwave Background are due to quantum mechanical fluctuations. T/F 2.The temperatures in the Cosmic Microwave Background are very different from place to place in the sky. T/F3.It took about a year for most of the hydrogen and helium to form from the Big Bang. T/F4.The Cosmic Microwave Background was emitted about 380,000 years after the Big Bang. T/F5.Dark matter is used to explain the accelerated expansion of the Universe. T/F

## What is the temperature for an almost completely absorbing dark planet at 1 AU and with a reflectivity of 7.0 %?

Question What is the temperature for an almost completely absorbing dark planet at 1 AU and with a reflectivity of 7.0 %? What is the escape velocity in km/s from Venus’ exosphere, which begins about 202 km above the surface? Assume the gravitational constant is G = 6.67 × 10-11m3 kg-1 s-2, and that Venus has a mass of 5.2e 24 kg and a radius of 6500.0 km.The Earth’s mid-ocean ridges create About 0.985 cm of new crust over their 1899 km length every year. How much new crustal area (in km2) will this process create in 108 years?What is the temperature for a very reflective, nearly white, planet with a reflectivity of 99.4 % at a distance of 1AU?A 0.894 km diameter asteroid will make a crater about 10 km in diameter. Let the asteroid have a density of 3000 kg/m3 and impact the surface at 16 km/sec. Assuming a spherical asteroid, what is the kinetic energy (in joule) of the asteroid? Convert the answer to megatons of TNT, where 1 megaton is about 4 × 1015joule. For comparison, the most energetic weapon in the human arsenal is about 100 megatons.What is the reflectivity (in percent) needed to keep water at a temperature near its freezing point of 265 K for a planet at 1 AU?

## If we knew that there was some friendly aliens on a planet 25 light

Question If we knew that there was some friendly aliens on a planet 25 light years away, and we sent a radio message to them, what’s the earliest time that we could expect a reply? -50 years. -1 year. -100 years. -We could hear back from them instantly. -25 years.