Maximum Speed - Physics - Past Paper, Exams of Physics

Download Maximum Speed - Physics - Past Paper and more Exams Physics in PDF only on Docsity! PHYSICS NYC SAMPLE FINAL EXAM PAGE 1 Section A – Each question is worth 1 mark 1. When an object is oscillating in simple harmonic motion in the vertical direction, its maximum speed occurs when the object A) is at its highest point. D) has the maximum net force exerted on it. B) is at its lowest point. E) has a position equal to its amplitude. C) is at the equilibrium point. 2. A clock keeps accurate time when the length of its simple pendulum is L. If the length of the pendulum is increased a small amount, which of the following is true? A) The clock will run slow. B) The clock will run fast. C) The clock will continue to keep accurate time. D) The answer cannot be determined without knowing the final length of the pendulum. E) The answer cannot be determined without knowing the percentage increase in the length of the pendulum. 3. During the passage of a longitudinal wave, a particle of the medium A) remains in a fixed position. B) moves in a circle. C) moves at right angles to the direction of propagation. D) moves forward and backward along the line of propagation. E) moves forward with the velocity of the wave. 4. A string under tension carries transverse waves traveling at speed v. If the same string is under four times the tension, what is the wave speed? A) v B) 2v C) v/2 D) 4v E) v/4 5. A wave is traveling with a speed v along the x axis in the positive direction. The upper graph shows the displacement y versus the distance x for a given instant of time. The lower graph shows the displacement y versus the time t for any given point x. From the information in the graphs, what is the wave speed v? A) 8.0 m/s B) 4.0 m/s C) 6.0 m/s D) There is not enough information to solve the problem. E) None of these is correct. PHYSICS NYC SAMPLE FINAL EXAM PAGE 2 6. We can hear sounds that are produced around a corner but cannot see light that is produced around a corner because A) light travels only in straight lines whereas sound can travel in a curved path. B) sound has more energy than light. C) sound has shorter wavelengths than light. D) sound has longer wavelengths than light. E) None of these is correct. 7. A sound source of frequency f moves with constant velocity (less than the speed of sound) through a medium that is at rest. A stationary observer hears a sound whose frequency is appreciably different from f because A) the equation that relates velocity of propagation, frequency, and wavelength of a sound traveling through a medium does not apply in this situation. B) the sound wave travels through the medium with a velocity different from that which it would have if the source were at rest. C) the frequency of the source is changed because of its motion. D) the wavelength established in the medium is not the same as it would be if the source were at rest. E) interference effects set up a standing-wave pattern that alters the frequency. 8. A string fixed at both ends is vibrating in a standing wave. There are three nodes between the ends of the string, not including those on the ends. The string is vibrating at a frequency that is its A) fundamental. D) fourth harmonic. B) second harmonic. E) fifth harmonic. C) third harmonic. 9. The velocity of escape of photoelectrons A) increases with increasing frequency of the incident light. B) decreases with increasing frequency of the incident light. C) is independent of the frequency of the incident light. D) is directly proportional to the intensity of the incident light. E) depends only on the intensity of the incident light. 10. The maximum kinetic energy of photoelectrons produced in the photoelectric effect depends directly on the A) frequency of the incident photons. B) intensity of the incident photons. C) area of the metal surface from which the photoelectrons are released. D) thickness of the metal. E) photoelectric current. PHYSICS NYC SAMPLE FINAL EXAM PAGE 5 Section B – Each question is worth 8 marks 1. A body of mass 4.00 kg is attached to a single spring of force constant k and is undergoing simple harmonic motion along the x-axis. The position vs time graph for this mass is shown below. (a) What is the angular frequency of the oscillation? (b) Using either a sine or cosine function write the equation of motion for the body putting in numerical values wherever possible . (c) What is the position of the body at t = 0.10 s? (d) What is the acceleration of the body at t = 0.10 s? (e) What is the force constant, k? .04 .06 -.04 x(m) t (s) .01 .02 .03 .04 .05 .06 .07 .08 .02 -.02 -.01 -.02 PHYSICS NYC SAMPLE FINAL EXAM PAGE 6 2. A simple pendulum of length 2.00 m with a mass of 1.50 kg is set up on a planet where the acceleration of gravity at the surface is unknown. The astronauts set the pendulum in motion so that it initially makes an angle of 0.100 radians with the vertical and starts from rest. They measure the angular frequency of the pendulum to be 1.186 s-1, (a) What is the period of the oscillation? (b) What is the linear velocity of the pendulum when it passes through the equilibrium position? (c) What is the acceleration due to gravity on the surface of this planet? (d) What is the total mechanical energy of the oscillation? PHYSICS NYC SAMPLE FINAL EXAM PAGE 7 3. (A) A string oscillates according to the equation ( , ) 0.50 sin( ) cos(40 ) 3 y x t x tπ π= , x is in cm and t in sec . (a) Write the equation of one of the two waves whose superposition gives this oscillation? (b) What is the internodal distance? 3.(B) A cord has two sections with linear densities of 0.10 kg/m and 0.20 kg/m respectively. An incident wave, y(x,t) = 0.050 sin ( 6.0 x – 12.0 t ) , where x is in meters and t in seconds, travels from the lighter cord to the heavier one . What is the wavelength of the wave in each section of the cord? 3.(C) If the amplitude of a sound wave is tripled, (a) By what factor will the intensity increase ? (b) By how many dB will the sound level increase ? PHYSICS NYC SAMPLE FINAL EXAM PAGE 10 6.(A) In a double-slit experiment, the slit separation is 0.160 mm and the width of each slit is 0.020 mm. The slits are illuminated at normal incidence with light of wavelength 600 nm and the resulting interference pattern is viewed on a screen located 2.00 m from the plane of the slits. (a) How many bright fringes are there in the central diffraction maximum? (b) The intensity of the light is measured at a point where X = 72.25 cm from the central maximum measured along the screen. What is the ratio of the intensity at this point to the intensity of the central maximum? (c) Draw the diagram showing the intensity as a function of the position. 6. (B) A square diffraction grating 5 cm x 5 cm has been ruled with 5000 lines/cm. (a) What is the resolving power of the grating in the third order if the entire grating is illuminated by the incident light? (b) If two monochromatic waves incident on this grating have a mean wavelength of 589.3 nm, what is their wavelength separation if they are just resolved in the third order? PHYSICS NYC SAMPLE FINAL EXAM PAGE 11 7.(A) For a rectangular metal surface with dimensions 5 cm by 3 cm, the threshold wavelength for the photoelectric emission of electrons is 246.0 nm. (a) Calculate the work function of the metal surface. (b) Calculate the wavelength of light that must be used in order for electrons with a maximum kinetic energy of 2.3 eV to be ejected. (c) If light of wavelength 300 nm and intensity 1.75 W/m2 is incident normally on the metal surface, calculate the number of photons that strike the surface in a time of 30 seconds. 7.(B) After colliding with a free electron an x-ray photon is scattered through an angle of 700. The wavelength of the scattered photon is 3.910 x 10- 12 m . (a) Calculate the Compton shift in wavelength. (b) What is the kinetic energy of the scattered electron? PHYSICS NYC SAMPLE FINAL EXAM PAGE 12 8.(A) Consider an electron confined to move back and forth along a line of length 0.090 nm. (a) What is the energy of the electron when it is in the second excited state? (b) What is the de Broglie wavelength of the electron in the second excited state? (c) Sketch the standing wave that represents the wave function of the electron in its second excited state. 8.(B) A hydrogen atom in an excited state has an energy, E = - 0.85 eV. It makes a transition to a different state where its energy is E = - 3.4 eV. (a) What are the quantum numbers of the two states? (b) What is the wavelength of the emitted photon? (c) Show this transition on an energy level diagram for hydrogen.