Final Exam 2003 Physics I



Name:__________________ Period:___

2011-2012 Physics I Exam Review- 2nd Semester

Momentum/Impulse/Collisions

__B__ 1. An ice skater initially skating at a velocity of 3 m/s speeds up to a velocity of 5 m/s. The momentum of the skater ________.

|a. |decreases |c. |remains the same |

|b. |increases |d. |becomes zero |

__C__ 2. If a force is exerted on an object, which statement is true?

|a. |A large force always produces a large change in the object’s momentum. |

|b. |A large force produces a large change in the object’s momentum only if the force is applied over a very short time |

| |interval. |

|c. |A small force applied over a long time interval can produce a large change in the object’s momentum. |

|d. |A small force produces a large change in the object’s momentum. |

__C__ 3. A constant impulse is applied to stop a moving shopping cart. Increasing the time interval over which the force is applied means that the stopping force is ________.

|a. |greater |c. |smaller |

|b. |unaffected |d. |the same |

__D__ 4. A 0.06 kg tennis ball moves at a velocity of 12 m/s. The ball is struck by a racket, causing it to rebound in the opposite direction at a speed of 18 m/s. What is the change in the ball’s momentum?

|a. |–0.38 kgm/s |c. |–1.1 kgm/s |

|b. |–0.72 kgm/s |d. |–1.8 kgm/s |

|Diagram: (Given + Unknowns) |Equation: impulse = m (vf – vi) |

|m = .06 kg | |

|vf = -18 m/s | |

|vi = 12 m/s | |

| |Substitute: |

| | |

| |impulse = m (vf – vi) |

| |Impulse = (.06kg)( -18 m/s - 12m/s) = - 1.8 kg m/s |

| | |

| | |

| | |Solve: Impulse = - 1.8 kg m/s |

_C___ 5. The impulse experienced by a body is equivalent to the body’s change in ________.

|a. |velocity |c. |momentum |

|b. |kinetic energy |d. |force |

_C___ 6. Which of the following are possible units for impulse?

a. kg m/s c. Both A and B

b. N s d. Neither A nor B

_B___ 7. A 75 kg person walking around a corner bumps into an 80 kg person running around the same corner. The momentum of the 80 kg person ________.

|a. |increases |c. |remains the same |

|b. |decreases |d. |is conserved |

__A__ 8. Two objects move separately after colliding, and both the total momentum and total kinetic energy remain constant. Identify the type of collision.

|a. |elastic |c. |Both A and B |

|b. |inelastic |d. |None of the above |

___B_ 9. Two objects collide and move together as one object after the collision, only the total momentum was conserved. Identify the type of collision.

|a. |elastic |c. |Both A and B |

|b. |inelastic |d. |None of the above |

__C__ 10. A swimmer with a mass of 75 kg dives off a raft with a mass of 500 kg. If the swimmer’s speed is 4 m/s immediately after leaving the raft, what is the speed of the raft?

|a. |0.2 m/s |c. |0.6 m/s |

|b. |0.5 m/s |d. |4.0 m/s |

|Diagram: (Given + Unknowns) |Equation: (m1+ m2) vi = m1v1 f + m2v2 f |

|Before After | |

|⃝ ( ○ + ● ( | |

|m1 = 75 kg v1 f = 4 m/s | |

|v i = 0 m/s | |

|m2 = 500 kg v2 f = ??? m/s | |

| | |

| | |

|In recoil, one object goes one direction while the other object goes | |

|the other direction. | |

| | |

|Newton’s 3rd law – for every action there is equal and opposite | |

|reaction | |

| |Substitute: |

| |(75 kg + 500 kg)(0 m/s) = (75 kg)(4.m/s) + (500kg)(vf) |

| |0 = 300 + 500vf |

| |-300 = 500vf |

| |-0.6 m/s = vf |

| | |

| | |

| |Note: speed is a scalar so our sign is ignored in the final answer. |

| | |Solve: 0.6 m/s = vf |

__A__ 11. A 4.0 kg bowling ball sliding to the right at 10.0 m/s has an elastic head-on collision with another 5.0 kg bowling ball initially at rest. The first bowling ball stops after the collision. Find the velocity of the second ball after the collision.

|a. |8.0 m/s |c . |35.0 m/s |

|b. |10.0 m/s |d. |40.0 m/s |

|Diagram: (Given + Unknowns) |Equation: m1v1 i + m2v2 i = m1v1 f + m2v2 f |

|Before After | |

|○ ( + ● ○ + ● ?? | |

|m1 = 4 kg v1 I = 10 m/s v2 f = 0 m/s | |

|m2 = 5 kg v2 I = 0 m/s v2 f = ?? m/s | |

| |Substitute: |

| |(4 kg)(10m/s) + (5kg)(0 m/s) = (4 kg)(0 m/s) + (5kg)vf |

| |40 + 0 = 0 + 5vf |

| |40 = 5vf |

| |8 m/s = vf |

| | |

| | |

| | |

| | |Solve: 8 m/s = vf |

__B__ 12. The impulse of 150 Ns is applied to a 10 kg object, what is the change of momentum on the object?

a. 15 kg m/s b. 150 kg m/s c. 1500 kg m/s d. 100 kg m/s.

| | | | |

| |SHM and WAVES | | |

13. When a wave crosses a boundary between a string and a rope, which wave properties are changed? (velocity, wavelength and or frequency) velocity and wavelength

Which property is not changed? frequency

14. When a wave passes from one medium to another and bends, what is this called? refraction

15. The diagram below shows what wave interaction? refraction

[pic]

| normal |

| |

| |

|Less Optically Dense |

|More Optically Dense |

| |

16 a. An incidence light ray (the arrow) is being refracted from more optically dense medium to a less optically dense medium. On the picture to the right, draw a normal line and draw an approximate refracted ray.

16 b. Does the refracted ray bend further or closer to the normal than the incident ray. The ray bends further from normal.

16 c. When compared to the incidence light ray, is the reflected light ray moving faster or slower than the incidence ray? It moves faster.

| normal |

| |

| |

|Less Optically Dense |

| More Optically Dense |

| |

17 a. An incident light ray (the arrow) is being refracted from less optically dense medium to a more optically dense medium. On the picture to the right, draw a normal line and draw an approximate refracted ray.

17 b. Does the refracted ray bend further or closer to the normal than the incident ray. The ray bends closer to normal.

17 c. When compared to the incidence light ray, is the

reflected light ray moving faster or slower than the incidence ray? It moves slower.

18. When a wave hits a boundary and bounces off, what is this called? reflection

19. You send continuous waves along a string of fixed length. As you decrease frequency, you increase (increase or decrease) wavelength λ.

( so how are frequency and wavelength related? inversely

20. For a TRANSVERSE wave, is the movement of particles Parallel or Perpendicular to the direction of wave propagation? perpendicular

21. For a LONGITUDINAL wave, is the movement of particles Parallel or Perpendicular to the direction of wave propagation? parallel

22. When a wave hits a FIXED end, like a wall, and is reflected, will it experience a PHASE change? YES YES YES

23. When a wave hits a FREE end and is reflected, will it experience a PHASE change? NO

24. On the diagram of the wave, please label the AMPLITUDE, CREST, TROUGH, EQUILIBRIUM, WAVELENGTH

[pic]

25. What is the primary difference between a Mechanical Wave and an Electromagnetic Wave?

Mechanical wave require a medium while electromagnetic wave do not necessarily need a medium.

26. Give one example of a mechanical wave. sound

27. Give one example of a electromagnetic wave. light

28. An ocean wave has a wavelength of 10 m. A wave passes a fixed location every 2.0 s. What is the speed of the wave?

|Diagram: (Given + Unknowns) |Equation: v = Δd / t |

| | |

|v = ??? m/s | |

|Δd = 10 m | |

|t = 2s | |

| |Substitute: |

| | |

| |v = 10 m / 2 s |

| | |Solve: v = 5 m/s |

29. List three examples of simple harmonic motion. Pendulum, mass bobbing up and down on a spring, skateboard going back and forth up and down a bowl

30. When two waves of opposite (crest and trough) amplitudes superpose, the result is called destructive interference. (constructive or destructive)

31. A simple pendulum swings in simple harmonic motion. At maximum displacement, describe the velocity, acceleration, and force. (max or zero)

Velocity zero Acceleration max Force max

32. Echoes are examples of reflection of sound waves.

33. Sound waves are longitudinal as well as mechanical waves.

34. A detected change in the frequency of a sound due to a moving source or a moving observer is called the Doppler effect.

35. Define ultrasonic. Define infrasonic.

Ultrasonic-- frequencies above human hearing

infrasonic -- frequencies below human hearing

36. A sound wave travels at 4500.0 m/s through a steel rod. What is the wavelength if its frequency is 2500.0 Hz?

|Diagram: (Given + Unknowns) |Equation: v = λf |

| | |

|v = 4500 m/s | |

|λ = ???? m | |

|f = 2500 Hz | |

| |Substitute: |

| | |

| |4500 m/s = λ (2500 Hz) |

| | |Solve: 1.8 m = λ |

37. Draw 2 uneven pulses, on the same side of a Slinky, before, during, and after superposition.

|Before |During |After |

| |[pic] |[pic] |

|[pic] | | |

38. Draw 2 even pulses, on opposite sides of a Slinky, before, during and after superposition.

|Before |During |After |

|[pic] |[pic] |[pic] |

LIGHT

39. Label each letter in the diagram. (normal, incident ray, angle of incidence, reflected ray, angle of reflection)

|A |Angle of incidence |

|B |Angle of reflection |

|C |Incident ray |

|D |Reflected ray |

|E |Normal |

40. All electromagnetic waves move at 3.0 x 108 m/s in a vacuum.

41. The fact that light can be polarized shows that light waves are transverse waves.

42. The bending of light waves from the sun as they pass through our atmosphere is an example of refraction. All angles are measure with respect to the normal at all times.

43. The ability of waves to spread around or through a barrier is called diffraction (reflection, refraction, or diffraction)

44. Draw a ray diagram for each of the following convex lenses. Please classify each Image as Real/Virtual, Reduced/Englarged, Upright/Inverted.

Real, inverted, reduced

45. Draw a ray diagram for each of the following convex lenses. Please classify each Image as Real/Virtual, Reduced/Englarged, Upright/Inverted.

Virtual, upright, enlarged

46. Converging lens are (thinner/thicker) thicker across its center than across its edges.

47. (Real/Virtual) Real images can be projected onto upon a screen while

(Real/Virtual) Virtual images can not be projected on a screen.

48. If a light ray travels from a more optically dense substance to a less optically dense substance, the light ray will (speed up/slow down) (circle one).

49. If a light ray travels from a more optically dense substance to a less optically dense substance, the light ray will (bend toward the normal/bend away from the normal) (circle one).

CHARGE and ELECTRICTY

50. What is an electrical conductor? An object which allows charges (usually electrons) to move through it.

51. What is an electrical insulator? An object that prevent the motion of charge

52. If a suspended object is attracted to another object which has a charge, what can you conclude? (2 things) at least one object is charged, and they are not both the same charge.

53. How does the electric force between two charges change when the distance between them is doubled? (does it increase or decrease) It decreases (by a factor of four actually)

54. How does the electrical force between two charges change when the charge of particle is tripled? (does it increase or decrease) It Increases. (By a factor of three actually)

55. What is the charge of a proton? +1 where is it located? In the nucleus

56. What is the charge of a neutron? 0 where is it located? In the nucleus

57. What is the charge of an electron? -1 where is it located? In the electron cloud or the orbital

58. If an ion of Ca+2 has a charge of +2,does it have more protons or electrons? More protons

59. Can you gain or lose protons? NO!!!!!!!! unless you are doing a nuclear reaction

Can you gain or lose electrons? Yes, those are chemical reactions

60. The rate of flow of electric charge, is the current.

61. Resistance is defined as opposition to charge movement.

62. If the length of the wire is doubled, will the amount of resistance increase or decrease? Resistance increases

63. If the diameter of a wire is doubled, will the amount of resistance increase or decrease? Resistance decreases

64. An ammeter registers 4.5 A of current in a wire that is connected to a 9.0 V battery. What is the wire’s resistance?

|Diagram: (Given + Unknowns) |Equation: V = IR |

| | |

|Vtotal = 9 V | |

|Itotal =4.5 A | |

|Rtotal = ?? Ω | |

| |Substitute: |

| | |

| |9 = (4.5) R |

| | |

| | |Solve: R = 2Ω |

65. What is the equivalent resistance of a series circuit with resistors of 7 Ω, 13 Ω, and 20Ω?

Rtotal = R1 + R2 + R3 = 40 Ω

66. What is the equivalent resistance of a parallel circuit with resistors of 7 Ω, 13 Ω, and 20Ω?

|Diagram: (Given + Unknowns) |Equation: 1/ Rtotal = 1/ R1 + 1 /R2 + 1 / R3 |

| | |

|Rtotal = ??? | |

|R1 = 7 Ω | |

|R2 = 13Ω | |

|R3 = 20 Ω | |

| |Substitute: |

| |1 = 1 + 1 + 1 1 = .1428 + .0769 + .05 |

| |Rtotal R1 R2 R3 Rtotal |

| | |

| |1 = 1 + 1 1 1 = .2697 (DO A SWITCHAROO) |

| |Rtotal 7 13 20 Rtotal |

| | |

| |1 = Rtotal |

| |.2697 |

| | |

| | |

| | |Solve: Rtotal = 3.7 Ω |

67. If you add more resistors in series, does your total resistance increase or decrease?

Total resistance increases

So, does your current drawn from the battery increase or decrease? Current decreases

68. If you add more resistors in parallel, does your total resistance increase or decrease

Total resistance decreases

So, does your current drawn from the battery increase or decrease? Current increases

69. An electric heater is operated by applying a potential difference of 50.0 V across a nichrome wire of total resistance 4.00 Ω. What is the power rating of the heater?

|Diagram: (Given + Unknowns) |Equation: V = IR P = IV |

|V = 50 V | |

|I =??? A | |

|R = 4 Ω | |

|P = ???? W | |

| |Substitute: |

| |I = V / R = 50 / 4 = 12.5 A |

| |P = IV = (12.5)(50) =625 W |

| | |Solve: P = 625 W |

70. Fill in the blanks in the chart.

|DEVICE |P |R |I |∆V |

|Computer |214 W |95 Ω |1.5 A |142 V |

|Portable Stereo |15.0 W |0.167 Ω |15 A |2.5 V |

|Coffee Maker |500.0 W |14 Ω |6.0 A |83 V |

|Graphing Calculator |0.126 W |198 Ω |.0252 A |V |

MAGNETS

71. When allowed to float freely, the North pole of a bar magnet points Geographic north toward a region in Canada because it is attracted to magnetic south.

72. The force experienced when the N-poles of two magnets are brought close together is what type of force? (attractive or repulsive) repulsive

73. If a bar magnet is broken into two pieces, how many poles does each magnet have? two

74. Is the magnetic field surrounding a current-carrying wire strongest closest to the wire or far from the wire? Probably near the poles and we usually describe a current carrying wire as having poles. The field surrounds the wire in a circle which has a direction but no ends

75. In the diagram below, the magnet labeled as #2 would have its N – pole facing what direction?

76. What device converts electrical energy into mechanical energy? motor

77. What device converts mechanical energy into electrical energy? generator

78. What device uses two coil wrapped round an iron core to change the voltage across a circuit? transformer

79. What process involves inducing voltage and current by changing the magnetic field around a conductor? Electromagnetic induction

80. How do identify a transformer as either a step up transformer or a step down transformer? Step up transformers increase the voltage by increasing the number of coils.

Step down transformers decrease the voltage by decreasing the number of coils

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amplitude

crest

wavelength

trough

equilibrium

[pic]

2f f f 2f

2f f f 2f

Upward

[pic]

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