Unit 3 Progress Check Physics

Unit 3 Progress Check Planet X has a mass of and a radius of . Planet Y has a mass of and a radius of . Identical satellites orbit both planets at a distance above their surfaces, as shown above. The planets are separated by such a large distance that the gravitational forces between them are negligible. 1. How does the magnitude of the gravitational force exerted by Planet Y on its satellite compare to the gravitational force exerted by Planet X on its satellite? (A) (B) (C) (D) 2. How does the gravitational field of Planet Y? (A) (B) (C) (D) at the surface of Planet X compare with the gravitational field at the surface A moon orbits a planet in a nearly circular orbit of radius 3. , as shown in the figure. Which of the following free-body diagrams could be used to analyze the forces exerted on the moon when it is at the position indicated in the figure? 5. Astronomers making careful observations of the moon’s orbit discover that the orbit is not perfectly circular, nor is it elliptical. Which of the following statements supports this observation? (A) The moon and the planet exert forces of equal magnitude on each other. (B) There is another celestial body that exerts a gravitational force on the moon. (C) The value of the gravitational constant (D) is different in the location near the planet-moon system. There is a centripetal force that causes the net force exerted on the moon to be different from the gravitational force. 6. Two containers of water can have their individual masses varied by adding or removing water. The containers are initially a distance apart, as measured from their centers, and are filled with water so that each has a mass , as shown in Figure 1 above. The gravitational force that one container exerts on the other is . Water is then added to one container so that its mass increases to , and water is removed from the other container so that its mass decreases to , as shown in Figure 2. What is the new gravitational force exerted on one container by the other? (A) (B) (C) (D) 7. Satellite orbits a planet at a distance from the planet’s center with a centripetal acceleration . A second identical satellite orbits the same planet at a distance from the planet’s center with centripetal acceleration What is the centripetal acceleration in terms of ? (A) (B) (C) (D) . Place the object on the edge of the disk. Set the disk to rotate at a tangential speed for the object such (A) that the object does not slide. Use a stopwatch to measure the time it takes for the object to make one revolution. Use a balance to determine the mass of the object. (B) Place the object on the disk and measure the distance from the center of the disk to the center of mass of the object by using a meterstick. Slowly increase the rate the disk rotates until the object begins to slide off the disk. Record the time in which the object makes one revolution around the center of the disk. Use a balance to determine the mass of the object. Place the object on the disk. Use a motion sensor placed above the disk to measure the tangential speed (C) the object rotates just after the mass begins to slide while increasing the rate at which the disk rotates. Use a balance to determine the mass of the object. Place the object on the disk and measure the distance from the center of the disk to the center of mass of (D) the object by using a meterstick. Slowly increase the rate the disk rotates until the object begins to slide off the disk. Record the time in which the object makes one revolution around the center of the disk. 12. An Atwood machine is placed on a planet in which the acceleration due to gravity on the planet is unknown. Both ends of a light string are attached to two blocks such that , and the string passes through a pulley such that frictional forces are considered to be negligible, as shown above. The same tension force is exerted on both blocks, and the block of mass experiences an acceleration in the downward direction when released from rest. Which quantities would allow the acceleration due to gravity on the planet to be determined? 13. (A) , (B) and , and only (C) and only (D) only A scientist designs an experiment that requires two atomic particles whose only fundamental force exerted between them is the gravitational force. Which combination of particles and separation distance will meet this condition? (A) A proton and neutron within an atomic nucleus (B) A proton and electron within the same atom (C) A proton and neutron located 1.0 mm apart (D) A proton and electron located 1.0 cm apart 14. A ball of Mass is swung in a vertical circle with a constant tangential speed. Figure 1 shows the forces exerted on the ball at the top of the circle, and Figure 2 shows the forces exerted on the ball at the bottom of the circle. Which of the following is an expression for the centripetal acceleration of the ball in terms of , , , and any fundamental constants? 17. A object is released from rest near the surface of a planet with a negligible atmosphere. A graph of the object’s speed as a function of time is shown. What is the weight of the object on the planet? (A) (B) (C) (D)