Physics Final Review

Transcription

1 Physics Final Review Mary Stangler Center for Academic Success Revised 10/31/13 Answer Key is located in the CAS. You must have attempted/completed 75% to see the answer key. Source: Wiley Plus and Physics 9e by Cutnell and Johnson 1. For a relay at a track meet, a runner runs 50 km North and hands off the baton to runner B. Runner B then runs 50 KM South of West. The two displacement Vectors A and B can be added together to give a resultant vector R. Which drawing correctly shows the resultant vector? 2. The displacement vectors C and D, when subtracted give us the resultant vector R, so that R=C-D. Use the data in the drawing and that θ=35 to find the magnitude and the direction (φ) of the resultant. 3. What it meant by magnitude? a. Force b. Measurement without direction c. A positive number d. Measurement with direction e. A and c f. A and B g. B and C

2 4. The top of a building is located H distance off the ground. Located half way up is the building is a balcony. A ball is thrown at the balcony with the same initial speed, either straight up from the ground or straight down from the top of the building. In the absence of air resistance, which stone hits the balcony in the least amount of time? 5. Using the accompanied graph, are v1 and v2 the same? 6. Each drawing shows the three points along the path of a rollercoaster, which is moving left to right. Ignoring air resistance and friction, which drawing correctly represents the acceleration a of the rollercoaster. 7. A rifle, at a height H above the ground, fires a bullet parallel to the ground. At the same instant and at the same height, a second bullet is dropped from rest. In the absence of air resistance, which bullet, if either, strikes the ground first? a. The first bullet b. The second bullet c. Both strike the ground at the same time.

3 8. Two forces act on moving object (with mass of 45 kg). One force has a magnitude of 13 N and points due North, while the other force has a magnitude of 19 N and points due east, what is the acceleration of the object? Include the direction of the acceleration. 9. In a galaxy far, far away there is a planet that has four times the earth s mass and three times the earth s radius. Luke s weight on this planet is times your earth-weight. Assume that the masses of the earth and of the other planet are uniformly distributed. 10. A penny is placed on a rotating turntable. Where on the turntable does the penny require the largest centripetal force to remain in place: at the center of the turntable or at the edge of the turntable? 11. Before Cybertron was destroyed, its two satellites orbited the planet. As the drawing shows one orbit has a radius r and the other has a radius of 3r. The centripetal force on the satellite with the larger radius is as that on the satellite in the smaller orbit.

4 12. The power needed to accelerate a projectile from rest to its speed v is W. How much power is needed to accelerate the same projectile from rest to 2v in a time of ½ t? Assume no change in height. 13. In her spacesuit on earth, an astronaut climbs up a vertical latter. On the moon, the astronaut does the same climb. During the climb, does the gravitational potential energy of the astronaut a. Change by a greater amount on earth b. Change by a greater amount of the moon c. The change is the same in both cases. 14. A multiple-stage rocket is moving in outer space with a momentum of kg m/s. There are no external forces acting on the rocket. The rocket then separates into two stages, each of which moves along the same direction (either forward or backward) as the initial rocket. The table lists 3 possibilities for the momenta of the two stages. There is only one possibility that can be correct. Which is it? Stage 1 Stage 2 A kg m/s kg m/s B kg m/s kg m/s C kg m/s kg m/s 15. A carousel at Valley Fair is a circular platform mounted parallel to the ground and can rotate about an axis that is perpendicular to the platform at its center. The angular speed of the carousel is contestant. Tommy is 1.2 m from the axis has a tangential speed of 1.9 m/s. What is the tangential speed of Sally, who is 2.2 m from the axis?

5 16. The radius of the circle traced out by the second hand on a clock is 4.00 cm. In a time t the tip of the second hand moves through an arc length of 21 cm. Determine the value of t in seconds. 17. Two Blocks are placed on a horizontal massless board. The board is kept from rotating and rests on a support that serves as an axis of rotation. The moment of inertia of this system is 14. Determine the angular acceleration when the system is allowed to rotate. 18. For a rigid body to be at equilibrium the a. Translational acceleration is? b. Angular acceleration is? c. Sum of externally applied forces (in each direction) is? d. The sum of externally applied torques is? 19. The drawing shows a top view of a door that is free to rotate about an axis of rotation that is perpendicular to the screen. Find the magnitude of the net torque produced by the forces about the axis.

6 20. Five simple pendulums are shown in the drawings. The lengths of the pendulums are drawn to scale, and the masses are either m, 2m, or 3m, as shown. Which pendulum(s) has the smallest angular frequency of oscillation? 21. Two rods are made from the same material and are the same length. One has a circular cross section, and the other has a square cross section. The circle just fits within the square. The same force is applied to stretch these rods, which rod, if either, is longer stretches more? 22. Blood flows through a section of a horizontal artery that is partially blocked by a deposit along the artery wall. As a hemoglobin molecule moves from the narrow region into the wider region, its speed changes from v 2 = m/s to v 1 = m/s. What is the change in pressure, P 1 - P 2, that it experiences? The density of blood is 1060 kg/m 3.

7 23. A beaker is filled to the brim with water. A solid object of mass 5.00 kg is lowered into the beaker so the object is fully submerged in the water (see the drawing). During this process, 4.00 kg of water flows over the rim and out of the beaker. What is the buoyant force that acts on the submerged object, and, when released, does the object rise, sink, or remain in place? 24. A rod is hung from an aluminum frame (α=23x10-6 ), as the drawing shows. The rod and the frame have the same temperature, and there is a small gap between the rod and the floor. The frame and rod are then heated uniformly. Will the rod ever touch the floor if the rod is made from a. Aluminum (α=23x10-6 )? b. Lead (α=29x10-6 )? c. Brass (α=19x10-6 )? 25. Which of the following cases (if any) requires the greatest amount of heat? In each case the material is the same. a. 5.0 kg of the material is to be heated by 3.4 C. b kg of the material is to be heated by 4 C. c. 8.5 kg of the material is to be heated by 2 C. d. 1.7 kg of the material is to be heated by 10 C. e. All of the above

8 26. The drawing shows a composite slab consisting of three materials through which heat is conducted from left to right. The materials have identical thicknesses and cross sectional areas. Rank the materials according to their thermal conductivities, largest first. a) k 1, k 2, k 3 b) k 3, k 2, k 1 c) k 1, k 3, k 2 d) K 2, K 3, K 1 e) K 2, K 1, K The two cubes in the drawing are made from the same material. The radiant energy per second emitted by the small cube is 4.0 J/s. What is the energy emitted per second by the larger one? 28. The pressure of a monatomic ideal gas is quadrupled, while the volume is cut in half. By what factor is the internal energy of the gas multiplied? b. 1 a. 2 b. 3 c. ½ 29. Carbon monoxide is a gas at 0 C and a pressure of Pa. It is a diatomic gas, each of its molecules consisting of one carbon atom (atomic mass = 12.0 u) and one oxygen atom (atomic mass = 16.0 u). Assuming that carbon monoxide is an ideal gas, calculate its density ρ.

9 30. The three Carnot engines shown in the drawing operate with hot and cold reservoirs whose temperature differences are 100 K. Rank the efficiencies of the engines, largest to smallest. a) A, B, C b) B, C, A c) All three have the same efficiencies d) C, B, A e) A, C, B 31. The drawing shows a pressure-volume graph for a gas being compressed. The area under the curve represents a. the change in the internal energy of the gas. b. the work done by the gas. c. the work done on the gas. d. the heat gained by the gas. e. the heat lost by the gas. 32. A rope is attached to a hook in the ceiling and is hanging straight down. The rope has a mass m, and nothing is attached to the free end of the rope. As a transverse wave travels down the rope from the top,. a. the speed of the wave decreases. b. the speed of the wave increases. c. the speed of the wave does not change. 33. What is the wavelength λ of a wave that has a speed of 349 m/s and a period of 14.2 ms? 34. Each of three tuning forks, A, B, and C, has a slightly different frequency. When A and B are sounded together, they produce a beat frequency of 7 Hz. When A and C are sounded together, they produce a beat frequency of 10 Hz. What is the smallest possible beat frequency when B and C are sounded together?