Q&A Hero

Q: Which of these atoms has the greatest number of electrons? A) helium B) carbon C) iron D) gold E) uranium

Q: Which of these atoms has the greatest amount of electrical charge in its nucleus? A) helium B) carbon C) iron D) gold E) uranium

Q: Which of these has the greatest number of protons in its nucleus? A) gold B) mercury C) lead D) silver

Q: The volume of matter is due mostly to its A) protons. B) electrons. C) both of these

Q: The mass of matter is due mostly to its A) protons. B) electrons. C) both of these

Q: Which of the following elements has the most mass? A) hydrogen B) iron C) lead D) uranium E) all have the same mass

Q: Which of the following is an inert gas? A) Hydrogen B) Helium. C) Carbon D) Oxygen

Q: Which of the following is a gas? A) lithium B) carbon C) neon D) sodium

Q: The number of protons in a neutral atom is balanced by an equal number of A) electron shells that surround the nucleus. B) neutrons in the nucleus. C) orbital electrons. D) none of the above

Q: Atomic number refers to the number of A) protons in the nucleus. B) neutrons in the nucleus. C) nucleons in the nucleus.

Q: A force that determines the chemical properties of an atom is A) a friction force. B) a nuclear force. C) a gravitational force. D) an electrical force. E) none of the above

Q: Although solid matter is mostly empty space, we don't fall through the floor because A) atoms are constantly vibrating, even at absolute zero. B) of nuclear forces. C) of gravitational forces. D) of electrical forces. E) none of the above

Q: Which is the smallest particle? A) molecule B) atom C) proton D) neutron E) quark

Q: An element is distinct because of its number of A) protons. B) neutrons. C) electrons. D) the total mass of all the particles. E) none of the above

Q: Which is the lightest particle? A) proton B) electron C) neutron D) all about the same

Q: Which of the following are electrically neutral? A) protons B) neutrons C) electrons D) ions E) none of the above

Q: Atoms heavier than helium were at one time manufactured by A) photosynthesis. B) thermonuclear fusion. C) radiant energy conversion. D) radioactivity. E) none of the above

Q: The element gold contains A) gold atoms. B) atoms that combine to produce gold. C) gold atoms plus various slightly lighter and heavier atoms. D) none of the above

Q: An atomic model of the atom is A) a symbolic representation of the atom. B) a stepping stone to further understanding. C) an abstraction enabling predictions. D) all of the above

Q: Atoms can be photographed by A) electron beams. B) scanning electron microscopes. C) both of these D) neither of these

Q: If we doubled the magnifying power of the most powerful optical microscope in the world, we would A) be able to see individual atoms. B) be able to photograph individual atoms, even though we couldn't see them. C) still not be able to see or photograph an atom.

Q: The difficulty of taking a photograph of an atom with light is A) unwanted diffraction. B) that atoms are smaller than wavelengths of light. C) both of these D) neither of these

Q: Which of the following statements is true? A) an atom is the smallest particle known to exist B) there are only about 100 different kinds of atoms that combine to form all substances C) there are thousands of different kinds of atoms that account for a wide variety of substances D) a large atom can be photographed with the aid of an ordinary microscope E) none of the above

Q: Assuming all the atoms exhaled by Julius Caesar in his last dying breath are still in the atmosphere, we breathe in at least one of them each A) single breath. B) day. C) month. D) ten years. E) can't say for some people breathe a few of Caesar's atoms daily, while others never.

Q: The chance that at least one of the atoms exhaled in your previous breath will be inhaled in your next breath is A) very low. B) very high. C) zero.

Q: A planet orbiting the Sun has speed v = √(GM/d). Escape speed from the Sun is v = √v(2GM/d), where G is the gravitational constant, M is Sun's mass, and d is the distance from the Sun. Noting that this tells us that escape speed is √2 times orbital speed, which planet would fly out of the solar system by a 1.5 increase in orbital speed? A) Mercury. B) Venus. C) Earth. D) all of the above E) none of the above

Q: The speed of a satellite orbiting Earth is given by v = √(GM/d). Escape speed from Earth is given by v = √(2GM/d), where in both cases G is the gravitational constant, M is Earth's mass, and d is distance from Earth's center. If a satellite's kinetic energy were doubled it could A) orbit at twice its distance from Earth. B) orbit at four times the distance from Earth. C) escape Earth.

Q: Which would require the greater energy; slowing the orbital speed of a satellite so it crashes into Earth, or increasing the orbital speed so it escapes Earth? A) slowing down B) speeding up C) same each way

Q: Which would require the greater change in a satellite's orbital speed (8 km/s); slowing down so it crashes into Earth, or speeding up so it escapes Earth? A) slowing down B) speeding up C) same each way D) need more information

Q: Pioneer 10 was able to escape the solar system by A) having a sufficient escape velocity at launch. B) "bouncing off" Jupiter like a tennis ball bouncing off an approaching tennis racket. C) refueling via solar cells. D) nuclear-powered sustained thrust.

Q: Consider a monkey wrench released at rest at the far edge of the solar system. Suppose that it drops to Earth by virtue of only Earth gravity. It will strike Earth's surface with a speed of about A) 10 m/s. B) 8 km/s. C) 11.2 km/s. D) the speed of light.

Q: To drop a package to Earth from a satellite, project it A) straight downward. B) ahead at satellite speed. C) behind at satellite speed. D) none of the above

Q: A vertically oriented rocket that is able to sustain a continuous upward velocity of 8 km/s will A) escape from Earth. B) be unable to escape Earth. C) eventually maintain a fixed orbit around Earth.

Q: A projectile that is fired vertically from the surface of Earth at 8 km/s will A) go into circular orbit about Earth. B) rise and fall back to Earth's surface. C) follow an uncertain path. D) escape from Earth.

Q: A projectile that is fired vertically from the surface of Earth at 5 km/s will A) go into circular about Earth. B) go into an elliptical orbit about Earth. C) rise and fall back to Earth's surface. D) none of the above

Q: Escape speed from Mars is A) about the same as from Earth. B) greater than from Earth. C) less than from Earth.

Q: Escape speed from the Moon is A) about the same as from Earth. B) much greater than from Earth. C) much less than from Earth.

Q: Escape speed from the Sun is A) about the same as from Earth. B) very much greater than for Earth. C) indefinite.

Q: Escape speed from Earth is A) 8 km/s. B) 9 km/s. C) 11.2 km/s. D) 63 km/s.

Q: A rocket coasts in an elliptical orbit about Earth. To attain escape velocity using the least amount of fuel in a brief firing time, should it fire off at the apogee, or at the perigee? (Hint: Let Fd = ∆ KE guide your thinking.) A) perigee, where it is closest and fastest B) apogee, where it is farthest and slowest C) same at either location D) same at any location

Q: Angular momentum is greater for a satellite when it is at the A) apogee (farthest point). B) perigee (nearest point). C) same at apogee and perigee

Q: Angular momentum is conserved for a satellite in A) circular orbit. B) elliptical orbit. C) both of these D) neither of these

Q: Rockets that launch satellites into orbit need less thrust when fired from A) Cape Canaveral in Florida. B) Edwards Air Force Base in California. C) Hawaii. D) location does not affect the required rocket thrust.

Q: The kinetic energy of a planet is maximum when it is A) closest to the Sun. B) farthest from the Sun. C) least accelerating. D) none of the above

Q: When the potential energy of a satellite decreases A) kinetic energy also decreases. B) its kinetic energy correspondingly increases. C) its distance from the orbiting body increases. D) none of the above

Q: The conservation of energy applies to satellites in A) circular orbit. B) elliptical orbit. C) both of these D) neither of these

Q: A satellite coasting at constant speed in a circular orbit A) is beyond the pull of Earth's gravity B) is nevertheless accelerating. C) undergoes changes in its potential energy. D) none of the above

Q: According to Kepler, the speed of a planet is slowest when it is A) closest to the Sun. B) farthest from the Sun. C) neither, for speed is a constant.

Q: According to Kepler, the orbital period of a planet is directly proportional to the A) planet's average distance from the Sun. B) square of the planet's average distance from the Sun. C) cube of the planet's average distance from the Sun.

Q: According to Kepler, the line from the Sun to any planet sweeps out equal areas of space A) with each complete revolution. B) only when the paths are ellipses. C) in equal time intervals.

Q: Who envisioned the motion of planets as projectiles obeying the laws of physics? A) Kepler B) Newton C) both of these D) neither of these

Q: The focal point of a satellite in orbit about the Sun is A) inside the Sun. B) outside the Sun. C) both of these D) neither of these

Q: Newton hypothesized that the forces acting on planets was A) along their directions of travel. B) perpendicular to their directions of travel. C) toward the Sun. D) none of the above

Q: Both Newton and Kepler considered forces on the planets. Kepler mistakenly hypothesized the direction of the forces to be A) along their directions of travel. B) perpendicular to their directions of travel. C) toward the Sun. D) none of the above

Q: According to Kepler, the paths of planets about the Sun are A) parabolas. B) circles. C) straight lines. D) ellipses. E) none of the above

Q: When Kepler devised his laws of planetary motion, he was most influenced by A) Galileo. B) Newton. C) Tycho Brahe.

Q: The orbital path of a satellite has two focal points. When both focal points are together A) the satellite path is an ellipse. B) the satellite path is a circle. C) satellites lose speed.

Q: For all paths of Earth satellites, one focus of the path is A) the location from which the satellite was launched. B) Earth's center. C) the Sun's center. D) need more information

Q: A satellite in an elliptical orbit about a planet travels much faster when it is directly over a A) large ocean. B) large island. C) high mountain range. D) great plain or plateau. E) none of the above

Q: An Earth satellite in an elliptical orbit has its smallest speed A) closest to Earth. B) when getting farther from Earth. C) when farthest from Earth. D) need more information

Q: Project a cannonball from atop Newton's hypothetical mountain at 8 km/s and it orbits Earth. Project it at 9 km/s and the shape of the orbit is A) a somewhat larger circle. B) a wide parabola. C) an ellipse.

Q: Consider a moon that orbits one of our most distant planets in an elliptical path. The distance that the moon covers each day is A) greatest when closest to the planet. B) greatest when farthest from the planet. C) the same everywhere. D) need more information

Q: Acceleration is greater for a satellite when it is at the A) apogee (farthest point). B) perigee (closest point). C) zenith. D) same acceleration at all of the above places.

Q: An Earth satellite in an elliptical orbit travels fastest when it is A) nearest Earth. B) farthest from Earth. C) everywhere along its orbit.

Q: The force of gravity does work on a satellite when it is in A) circular orbit. B) elliptical orbit. C) both of these D) neither of these

Q: Which of these vary for satellites in elliptical orbits? A) speed. B) momentum. C) kinetic energy. D) all of the above E) none of the above

Q: Which of these vary for satellites in circular orbits? A) speed. B) momentum. C) kinetic energy. D) all of the above E) none of the above

Q: From Earth, one satellite appears to overtake another. The faster satellite is A) higher. B) lower. C) smaller. D) can't say

Q: Compared with the period of satellites in close Earth orbit, the period of satellites orbiting far from Earth is A) shorter. B) the same. C) longer. D) need more information

Q: Communications and weather satellites always appear at the same place in the sky, because these satellites are A) beyond the pull of Earth's gravitational field. B) moving at a speed just short of escape velocity. C) orbiting Earth with a 24-hour period. D) stationary in space. E) none of the above

Q: The Early Bird communication satellite hovers over the same point on Earth's equator indefinitely, because A) other forces than Earth's gravity act on it. B) it pulls as hard on Earth as Earth pulls on it. C) it is beyond the main pull of Earth gravity. D) it is kept aloft by ground control. E) its orbital period is 24 hours.

Q: An Earth satellite in close orbit circles Earth in about an hour and a half. How long would a satellite located as far away as the Moon take to orbit Earth? A) the same hour and a half B) less than an hour and a half C) about 28 days D) need more information E) none of the above

Q: The period of an Earth satellite depends on the satellite's A) mass. B) weight on Earth. C) radial distance from Earth. D) all of the above E) none of the above

Q: Minimal orbit speed about Earth is about 8 km/s, and about Jupiter is A) less than 8 km/s. B) more than 8 km/s. C) about 8 km/s.

Q: Minimal orbital speed about Earth is about 8 km/s, and about the Moon is A) less than 8 km/s. B) more than 8 km/s. C) about 8 km/s.

Q: If a satellite's radial velocity is zero at all times, its orbit must be A) parabolic. B) elliptical. C) circular. D) geosynchronous.

Q: The circular path of a satellite orbiting Earth is characterized by a constant A) speed. B) acceleration. C) radial distance. D) all of the above E) none of the above

Q: Earth satellites are typically more than 100 km high so as to be above Earth's A) atmosphere. B) gravitational field. C) both of these

Q: Acceleration due to gravity on the Moon is less than on Earth, and the Moon is smaller than Earth. This means that compared to an Earth satellite, a satellite in close orbit about the Moon would travel A) slower. B) faster. C) the same. D) need more information

Q: The speed of an Earth satellite does NOT depend on its A) distance from Earth. B) mass. C) but it depends on both D) it depends on neither