 ## Quantum Theory – Full Documentary HD

Check: https://youtu.be/Hs_chZSNL9I The World of Quantum – Full Documentary HD http://www.advexon.com For more Scientific DOCUMENTARIES. Subscribe for more Videos… Quantum mechanics (QM — also known as quantum physics, or quantum theory) is a branch of physics which deals with physical phenomena at nanoscopic scales where the action is on the order of the Planck constant.…

## 13.62 . (a) Calculate how much work is required to launch a spacecraft of mass m from the surface of the earth (mass mE radius RE) and place it in a circular low earth orbit—that is an orbit whose altitude above the earth’s surface is much less than RE. (As an example the International Space Station is in low earth orbit at an altitude of about 400 km much less than RE = 6370 km.) Ignore the kinetic energy that the spacecraft has on the ground due to the earth’s rotation. (b) Calculate the minimum amount of additional work required to move the spacecraft from low earth orbit to a very great distance from the earth. Ignore the gravitational effects of the sun the moon and the other planets. (c) Justify the statement “In terms of energy low earth orbit is halfway to the edge of the universe.”

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.61 . Falling Hammer. A hammer with mass m is dropped from rest from a height h above the earth’s surface. This height is not necessarily small compared with the radius RE of the earth. Ignoring air resistance derive an expression for the speed y of the hammer when it reaches the earth’s surface. Your expression should involve h RE and mE (the earth’s mass).

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.60 … Mass of a Comet. On July 4 2005 the NASA spacecraft Deep Impact fired a projectile onto the surface of Comet Tempel 1. This comet is about 9.0 km across. Observations of surface debris released by the impact showed that dust with a speed as low as 1.0 m>s was able to escape the comet. (a) Assuming a spherical shape what is the mass of this comet? (Hint: See Example 13.5 in Section 13.3.) (b) How far from the comet’s center will this debris be when it has lost (i) 90.0% of its initial kinetic energy at the surface and (ii) all of its kinetic energy at the surface?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.59 … An unmanned spacecraft is in a circular orbit around the moon observing the lunar surface from an altitude of 50.0 km (see Appendix F). To the dismay of scientists on earth an electrical fault causes an on-board thruster to fire decreasing the speed of the spacecraft by 20.0 m>s. If nothing is done to correct its orbit with what speed (in km>h) will the spacecraft crash into the lunar surface?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.58 .. The 0.100-kg sphere in Fig. P13.58 is released from rest at the position shown in the sketch with its center 0.400 m from the center of the 5.00-kg mass. Assume that the only forces on the 0.100-kg sphere are the gravitational forces exerted by the other two spheres and that the 5.00-kg and 10.0-kg spheres are held in place at their initial positions. What is the speed of the 0.100-kg sphere when it has moved 0.400 m to the right from its initial position?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.57 .. CP You are exploring a distant planet. When your spaceship is in a circular orbit at a distance of 630 km above the planet’s surface the ship’s orbital speed is 4900 m>s. By observing the planet you determine its radius to be 4.48 * 106 m. You then land on the surface and at a place where the ground is level launch a small projectile with initial speed 12.6 m>s at an angle of 30.8_ above the horizontal. If resistance due to the planet’s atmosphere is negligible what is the horizontal range of the projectile?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.56 … CP Your starship the Aimless Wanderer lands on the mysterious planet Mongo. As chief scientist-engineer you make the following measurements: A 2.50-kg stone thrown upward from the ground at 12.0 m>s returns to the ground in 4.80 s; the circumference of Mongo at the equator is 2.00 * 105 km; and there is no appreciable atmosphere on Mongo. The starship commander Captain Confusion asks for the following information: (a) What is the mass of Mongo? (b) If the Aimless Wanderer goes into a circular orbit 30 000 km above the surface of Mongo how many hours will it take the ship to complete one orbit?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.55 .. CP An astronaut whose mission is to go where no one has gone before lands on a spherical planet in a distant galaxy. As she stands on the surface of the planet she releases a small rock from rest and finds that it takes the rock 0.480 s to fall 1.90 m. If the radius of the planet is 8.60 * 107 m what is the mass of the planet?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.54 … (a) Suppose you are at the earth’s equator and observe a satellite passing directly overhead and moving from west to east in the sky. Exactly 12.0 hours later you again observe this satellite to be directly overhead. How far above the earth’s surface is the satellite’s orbit? (b) You observe another satellite directly overhead and traveling east to west. This satellite is again overhead in 12.0 hours. How far is this satellite’s orbit above the surface of the earth?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.53 .. Planet X rotates in the same manner as the earth around an axis through its north and south poles and is perfectly spherical. An astronaut who weighs 943.0 N on the earth weighs 915.0 N at the north pole of Planet X and only 850.0 N at its equator. The distance from the north pole to the equator is 18 850 km measured along the surface of Planet X. (a) How long is the day on Planet X? (b) If a 45 000-kg satellite is placed in a circular orbit 2000 km above the surface of Planet X what will be its orbital period?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.52 … A landing craft with mass 12 500 kg is in a circular orbit 5.75 * 105 m above the surface of a planet. The period of the orbit is 5800 s. The astronauts in the lander measure the diameter of the planet to be 9.60 * 106 m. The lander sets down at the north pole of the planet. What is the weight of an 85.6-kg astronaut as he steps out onto the planet’s surface?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.51 … What is the escape speeda 300-km-diameter asteroid with a density of 2500 kg>m3?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.50 .. CP Submarines on Europa. Some scientists are eager to send a remote-controlled submarine to Jupiter’s moon Europa to search for life in its oceans below an icy crust. Europa’s mass has been measured to be 4.80 * 1022 kg its diameter is 3120 km and it has no appreciable atmosphere. Assume that the layer of ice at the surface is not thick enough to exert substantial force on the water. If the windows of the submarine you are designing each have an area of 625 cm2 and can stand a maximum inward force of 8750 N per window what is the greatest depth to which this submarine can safely dive?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.49 . Geosynchronous Satellites. Many satellites are moving in a circle in the earth’s equatorial plane. They are at such a height above the earth’s surface that they always remain above the same point. (a) Find the altitude of these satellites above the earth’s surface. (Such an orbit is said to be geosynchronous.) (b) Explain with a sketch why the radio signals from these satellites cannot directly reach receivers on earth that are north of 81.3_ N latitude.

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.48 … At a certain instant the earth the moon and a stationary 1250-kg spacecraft lie at the vertices of an equilateral triangle whose sides are 3.84 * 105 km in length. (a) Find the magnitude and direction of the net gravitational force exerted on the spacecraft by the earth and moon. State the direction as an angle measured from a line connecting the earth and the spacecraft. In a sketch show the earth the moon the spacecraft and the force vector. (b) What is the minimum amount of work that you would have to do to move the spacecraft to a point far from the earth and moon? Ignore any gravitational effects due to the other planets or the sun.

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.47 … CP An experiment is performed in deep space with two uniform spheres one with mass 50.0 kg and the other with mass 100.0 kg. They have equal radii r = 0.20 m. The spheres are released from rest with their centers 40.0 m apart. They accelerate toward each other because of their mutual gravitational attraction. You can ignore all gravitational forces other than that between the two spheres. (a) Explain why linear momentum is conserved. (b) When their centers are 20.0 m apart find (i) the speed of each sphere and (ii) the magnitude of the relative velocity with which one sphere is approaching the other. (c) How far from the initial position of the center of the 50.0-kg sphere do the surfaces of the two spheres collide?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.46 .. Mission to Titan. On December 25 2004 the Huygens probe separated from the Cassini spacecraft orbiting Saturn and began a 22-day journey to Saturn’s giant moon Titan on whose surface it landed. Besides the data in Appendix F it is useful to know that Titan is 1.22 * 106 km from the center of Saturn and has a mass of 1.35 * 1023 kg and a diameter of 5150 km. At what distance from Titan should the gravitational pull of Titan just balance the gravitational pull of Saturn?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.45 .. A uniform sphere with mass 50.0 kg is held with its center at the origin and a second uniform sphere with mass 80.0 kg is held with its center at the point x = 0 y = 3.00 m. (a) What are the magnitude and direction of the net gravitational force due to these objects on a third uniform sphere with mass 0.500 kg placed at the point x = 4.00 m y = 0? (b) Where other than infinitely far away could the third sphere be placed such that the net gravitational force acting on it from the other two spheres is equal to zero?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.44 … CP Exploring Europa. There is strong evidence that Europa a satellite of Jupiter has a liquid ocean beneath its icy surface. Many scientists think we should land a vehicle there to search for life. Before launching it we would want to test such a lander under the gravity conditions at the surface of Europa. One way to do this is to put the lander at the end of a rotating arm in an orbiting earth satellite. If the arm is 4.25 m long and pivots about one end at what angular speed (in rpm) should it spin so that the acceleration of the lander is the same as the acceleration due to gravity at the surface of Europa? The mass of Europa is 4.80 * 1022 kg and its diameter is 3120 km.

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.43 . Three uniform spheres are fixed at the positions shown in Fig. P13.43. (a) What are the magnitude and direction of the force on a 0.0150-kg particle placed at P? (b) If the spheres are in deep outer space and a 0.0150-kg particle is released from rest 300 m from the origin along a line 45_ below the -x@axis what will the particle’s speed be when it reaches the origin?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.42 … Four identical masses of 8.00 kg each are placed at the corners of a square whose side length is 2.00 m. What is the net gravitational force (magnitude and direction) on one of the masses due to the other three?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.41 … Neutron stars such as the one at the center of the Crab Nebula have about the same mass as our sun but have a much smaller diameter. If you weigh 675 N on the earth what would you weigh at the surface of a neutron star that has the same mass as our sun and a diameter of 20 km?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.40 . In 2005 astronomers announced the discovery of a large black hole in the galaxy Markarian 766 having clumps of matter orbiting around once every 27 hours and moving at 30 000 km>s. (a) How far are these clumps from the center of the black hole? (b) What is the mass of this black hole assuming circular orbits? Express your answer in kilograms and as a multiple of our sun’s mass. (c) What is the radius of its event horizon?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.39 .. At the Galaxy’s Core. Astronomers have observed a small massive object at the center of our Milky Way galaxy (see Section 13.8). A ring of material orbits this massive object; the ring has a diameter of about 15 light-years and an orbital speed of about 200 km>s. (a) Determine the mass of the object at the center of the Milky Way galaxy. Give your answer both in kilograms and in solar masses (one solar mass is the mass of the sun). (b) Observations of stars as well as theories of the structure of stars suggest that it is impossible for a single star to have a mass of more than about 50 solar masses. Can this massive object be a single ordinary star? (c) Many astronomers believe that the massive object at the center of the Milky Way galaxy is a black hole. If so what must the Schwarzschild radius of this black hole be? Would a black hole of this size fit inside the earth’s orbit around the sun?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.38 .. Mini Black Holes. Cosmologists have speculated that black holes the size of a proton could have formed during the early days of the Big Bang when the universe began. If we take the diameter of a proton to be 1.0 * 10-15 m what would be the mass of a mini black hole?

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.

## 13.37 . The acceleration due to gravity at the north pole of Neptune is approximately 11.2 m>s2. Neptune has mass 1.02 * 1026 kg and radius 2.46 * 104 km and rotates once around its axis in about 16 h. (a) What is the gravitational force on a 3.00-kg object at the north pole of Neptune? (b) What is the apparent weight of this same object at Neptune’s equator? (Note that Neptune’s “surface” is gaseous not solid so it is impossible to stand on it.)

University Physics with Modern Physics lessons by JJtheTutor. Designed to teach students problem solving skills, test taking skills and how to understand the concepts.