NY Regents January 2008, Part 3
41. Which graph best represents the relationship between the elastic potential energy stored in a spring and its elongation from equilibrium?
42. A car with mass m possesses momentum of magnitude p. Which expression correctly represents the kinetic energy, KE, of the car in terms of m and p?

Base your answers to questions 43 and 44 on the information and diagram below.

Two small metallic spheres, A and B, are separated by a distance of 4.0 × 10–1 meter, as shown. The charge on each sphere is +1.0 × 10–6 coulomb. Point P is located near the spheres.

43. What is the magnitude of the electrostatic force between the two charged spheres?
44. Which arrow best represents the direction of the resultant electric field at point P due to the charges on spheres A and B?

45. A particle unaffected by an electric field could have a quark composition of
46. An electrical appliance draws 9.0 amperes of current when connected to a 120-volt source of potential difference. What is the total amount of power dissipated by this appliance?
47. A sound wave has a wavelength of 5.5 meters as it travels through air at STP. What is the wavelength of this sound in a medium where its speed is 1324 meters per second?
48. Which graph best represents the relationship between energy and mass when matter is converted into energy?
49. Which diagram best represents the behavior of a ray of monochromatic light in air incident on a block of crown glass?

 50. A spring in a toy car is compressed a distance, x. When released, the spring returns to its original length, transferring its energy to the car. Consequently, the car having mass m moves with speed v.   Assuming an ideal mechanical system with no loss of energy, derive the spring constant, k, of the car’s spring in terms of m, x, and v. Show all work, including the equations used to derive the spring constant.

 Base your answers to questions 51 and 52 on the information below.   A 75-kilogram athlete jogs 1.8 kilometers along a straight road in 1.2 × 103 seconds.   51. Determine the average speed of the athlete in meters per second.

 52. Calculate the average kinetic energy of the athlete. Show all work, including the equation and substitution with units.

 Base your answers to questions 53 and 54 on the information below.   A copper wire at 20°C has a length of 10.0 meters and a cross-sectional area of 1.00 × 10–3 meter2. The wire is stretched, becomes longer and thinner, and returns to 20°C.   53. What effect does this stretching have on the wire’s resistance?

 54. What effect does this stretching have on the wire’s resistivity?

 55. A car, initially traveling at 30. meters per second, slows uniformly as it skids to a stop after the brakes are applied. On the axes in your answer booklet, sketch a graph showing the relationship between the kinetic energy of the car as it is being brought to a stop and the work done by friction in stopping the car.

 Base your answers to questions 56 and 57 on the information and diagram below.     Two plane mirrors are positioned perpendicular to each other as shown. A ray of monochromatic red light is incident on mirror 1 at an angle of 55°. This ray is reflected from mirror 1 and then strikes mirror 2.   56. Determine the angle at which the ray is incident on mirror 2.

 57. On the diagram in your answer booklet, use a protractor and a straightedge to draw the ray of light as it is reflected from mirror 2.

 Base your answers to questions 58 and 59 on the information and diagram below.   A soccer ball is kicked from point Pi at an angle above a horizontal field. The ball follows an ideal path before landing on the field at point Pf .   58. On the diagram in your answer booklet, draw an arrow to represent the direction of the net force on the ball when it is at position X. Label the arrow Fnet. [Neglect friction.]

 59. On the diagram in your answer booklet, draw an arrow to represent the direction of the acceleration of the ball at position Y. Label the arrow a. [Neglect friction.]

 60. A 1500-kilogram car accelerates at 5.0 meters per second2 on a level, dry, asphalt road. Determine the magnitude of the net horizontal force acting on the car.

 61. Calculate the magnitude of the centripetal force acting on Earth as it orbits the Sun, assuming a circular orbit and an orbital speed of 3.00 × 104 meters per second. Show all work, including the equation and substitution with units.

 62. A tau lepton decays into an electron, an electron antineutrino, and a tau neutrino, as represented in the reaction below.     On the equation in your answer booklet, show how this reaction obeys the Law of Conservation of Charge by indicating the amount of charge on each particle.