Complete as much as you can. All questions are based on the physics involved in window boxes, and should be in your book!

1. Figure 1 shows a block on an inclined plane. If the plane is inclined so that the block is right at the point of sliding, what is the coefficient of friction?

1. μ = 0.25
2. μ = 0.50
3. μ = 0.67

4. Figure 1

   μ = 0.75

2. Figure 2 shows the free body diagram for the block in figure 1, right at the point that it is about to slide. Which of the following represents the Reaction?

1. R = 58.8 N
2. R = 73.5 N
3. R = 78.4 N
4. R = 98.0 N

3. Which of the following represents the Friction?

1. Fr = 58.8 N
2. Fr = 49.0 N
3. Fr = 73.5 N
4. Fr = 0 N (because the block is stationary)

4. What is the Mechanical Advantage of the inclined plane in figure 1, assuming that the coefficient of friction is zero?

1. M.A. = 0.75
2. M.A. = 0.80
3. M.A. = 1.25
4. M.A. = 1.67

5. A wheel of radius 0.5 meters is rolling on a road, making one revolution per second. What is the linear speed of the wheel?

1. v = 1.00 m/s
2. v = 1.57 m/s
3. v = 3.14 m/s
4. v = 6.28 m/s

6. If the coefficient of friction between the wheel and the road is μ = 1.2, what is the angle of the steepest incline that the wheel could roll up without slipping?

1. θ = 30º
2. θ = 40º
3. θ = 50º
4. θ = 60º

7. Figure 3 shows a crank handle which is driving a belt via a toothed gear. What is the mechanical advantage (M.A.) of the crank-gear arrangement?

1. M.A. = 6.67
2. M.A. = 1.20
3. M.A. = 0.15
4. M.A. is impossible to calculate without knowing the number of teeth on the gear.

8. What is the angular velocity that the crank must turn at if the belt is to have a linear velocity of v = 15 cm/s?

1. ω = 0.125 radians per second
2. ω = 1.25 radians per second
3. ω = 12.5 radians per second
4. ω = 125 radians per second

9. A fairground carousel has a radius of 6 meters. If it makes one revolution every 10 seconds, what is the linear velocity that riders are moving at?

1. v = 3.77 m/s
2. v = 4.88 m/s
3. v = 5.99 m/s
4. v = 7.00 m/s

10. The carousel is spun just fast enough to give riders at the top a complete sense of weightlessness. How long does the ride now take to make one complete revolution?

1. τ = 1.2 seconds
2. τ = 2.8 seconds
3. τ = 3.6 seconds
4. τ = 4.9 seconds

11. A 15 kg mass is attached to a spring whose natural length is 0.09 m. The mass hangs under gravity and the spring stretches to a new length of 0.15 m. Which of the following is the best value for the spring constant?

1. k = 2.25 N/m
2. k = 2.45 N/m
3. k = 245 N/m
4. k = 2450 N/m

12. The mass is pulled down a further 4 cm and then released. What is the frequency of the oscillations that the mass on the spring undergoes?

1. f = 2.03 Hz
2. f = 20.3 Hz
3. f = 203 Hz
4. f = 2.03 kHz
12. Which of the following best sums up fluorescence?

1. Two low energy infra-red photons are absorbed by a single atom which then emits one high energy ultraviolet photon.
2. The energy from one high energy ultraviolet photon is shared between two atoms which each emit a visible photon.
3. A light beam is amplified when passing through a region of optically excited atoms, causing them to emit light of the same frequency as the original beam.
4. A single atom absorbs a high energy photon, which triggers the emission of a single, lower energy photon.

14. What is meant by the term band gap in an LED?

1. The space between the reflective surfaces in the optical cavity.
2. The wavelength of the light coming from the LED
3. The energy difference between valence electron state and the conduction state
4. The physical separation between the p-type and n-type doped material.

15. Figure 4 shows a string wrapped around a one inch diameter pole, to which a handle is attached. A 15 Newton Force is applied 8 inches from the center of the pole. What is the tension in the string?

1. T = 15 N
2. T = 120 N
3. T = 240 N
4. T = 480 N

16. The string is plucked off-center. The fundamental frequency is found to be 280 Hz. If the Force applied to the handle is doubled, what is the new frequency of vibration?

1. f = 140 Hz
2. f = 396 Hz
3. f = 485 Hz
4. f = 560 Hz

17. If the string is plucked dead-center, which of the following modes are exited in the string?

1. The fundamental and the even harmonics
2. The fundamental and the odd harmonics
3. All of the harmonics, but not the fundamental
4. Only the odd harmonics, and no fundamental

18. A strobe is set to flash every 20 milliseconds (1 millisecond = 1 x 10^-3 seconds). Which of the following string frequencies would appear stationary?

1. f = 50 Hz
2. f = 60 Hz
3. f = 70 Hz
4. f = 80 Hz
18. Which of the following statements is true about a resonant box when coupled to a tuning fork?

1. The box puts energy into the vibrating fork, causing vibrations to last longer.
2. The box channels energy out of the fork in the form of audible sound.
3. The box isolates the fork from the ground, reducing gravitational interference.
4. The box converts a longitudinal vibration in the fork to a transverse vibration in the air.

20. If tuning fork A produces a note one octave higher than tuning fork B, which of the following must be true?

1. Tuning fork A must vibrate at twice the frequency of tuning fork B
2. Tuning fork A must vibrate at half the frequency of tuning fork B
3. Tuning fork A must be made of less dense material than tuning fork B
4. Tuning fork A must have been hit twice as hard as tuning fork B

21. A laser has a spot size of 1.2 mm. After reflection from a number of back-silvered mirrors, the spot appears diffuse, and has a size of 8.3 mm. This is most likely due to:

1. Rayleigh scattering of the beam by particles in the air.
2. Gaussian beam divergence arising from a too narrow laser aperture.
3. Photon-photon interactions in a beam of unusually high energy-density.
4. Multiple reflections at air-glass interfaces.

22. A laser is shone through a super-fast mechanical shutter that opens and closes in a time of  (1/8000) second. What is the physical length of the light beam generated?

1. Distance = 38 micrometers (38 x 10^-6 m)
2. Distance = 38 millimeters (38 x 10^-3 m)
3. Distance = 38 meters
4. Distance = 38 kilometers

23. The word laser is an acronym for:

1. Light And Sound Energy Ray
2. Light Amplification by Stimulated Emission of Radiation
3. Light Activation with Simultaneous Emission of Radiation
4. Laser Action by Synthesis of Energy Radiation

24. A red apple appears red because:

1. Pigments in the apple skin absorb all colors other than red.
2. Pigments in the apple emit red light.
3. Pigments in the apple skin fool our brains into thinking we see red.
4. Atoms in the apple skin absorb all the long wavelength white photons, and convert them all into short wavelength red photons.

25. A single plane mirror will:

1. Always create a virtual image.
2. Always create a real image.
3. Create a virtual or real image, depending on where the object is placed
4. Create more than one image. The terms virtual and real simply depend on which side of the mirror you are standing.

26. A single concave parabolic mirror will:

1. Always create a virtual image
2. Always create a real image
3. Create a virtual or real image, depending on where the object is placed
4. Create more than one image. The terms virtual and real simply depend on which side of the mirror you are standing.

27. A double convex lens by itself will:

1. Always create a virtual image
2. Always create a real image
3. Create a virtual or real image, depending on where the object is placed
4. Create more than one image. The terms virtual and real simply depend on which side of the lens you are standing.

28. A double convex convergent lens with a focal length of f = 10 cm is to be used to project an image from a slide onto a screen 2 meters from the lens. At what distance behind the lens should the slide be placed?

1. u = 105 mm.
2. u = 110 mm.
3. u = 95 mm.
4. u = 100 mm.

29. The image of the slide in question 29 will be:

1. Real, diminished, and inverted.
2. Real, enlarged and inverted.
3. Real, enlarged and the right way up.
4. Virtual, enlarged and the right way up.

30. Which of the following best explains why the laser in the mirror box appears green?

1. The light is emitted over a very broad spectral range that causes all the rods in the eye to fire, but mostly the ones tuned to green.
2. The light is emitted over a fairly broad spectral range that causes the yellow and blue rods in the eye to fire most, so the brain interprets green.
3. The light is emitted over a relatively narrow part of the spectrum that causes only the yellow and blue rods in the eye to fire, so the brain interprets green.
4. The light is emitted over a very narrow part of the spectrum that causes only the green rods in the eye to fire.

31. Draw rays to locate the image of the object O in the set-up below.

32. Draw rays to locate the image of the object O in the set-up below.

33. On each arm of a chaotic pendulum there is a smaller pendulum. The smaller pendulums consist of 0.06 kg masses a distance 0f 0.05 m from the pivot point. When the main arm is not moving, what is the period of oscillation of these pendulums?

1. τ = 0.032 seconds
2. τ = 0.081 seconds
3. τ = 0.45 seconds
4. τ = 0.8 seconds

34. A simple differential in a car transmission system:

1. Allows tires to turn at different rate when turning a corner.
2. Prevents tires from spinning when a car is stuck in mud.
3. Always delivers the same amount of power to each wheel.
4. Controls the coefficient of friction between the tire and the road.

35. The probability of the ball in Ballin going left-left-left-left-left (ie- left five times in a row) on its first 5 drops is:

1. Approximately  132%
2. Approximately  30%
3. Approximately  3%
4. Approximately  0.03%

36. A ball in Ballin dropping through the first six levels goes left-left-left-right-left-right. How many different paths could the ball have gone from the first pin to end up at the same point after 6 drops?

1. Only 1 other path.
2. 14 other paths.
3. 19 other paths.
4. 21 other paths.

37. Electro-magnetic eddy currents can be formed in:

1. Any metal object moving through a static magnetic field.
2. Any metal object but ONLY when it moves through an oscillating magnetic field.
3. Only non-ferrous metals.
4. The transpiration and evaporation stages of the water cycle.

38. A certain amount of gas is compressed from a volume of V₁ = 0.5 m³ to V₂ = 0.2 m³. If the temperature is kept constant during the entire process, which of the following is true:

1. The pressure will increase by a factor greater than 2
2. The pressure will increase by a factor between 1.5 and 2
3. The pressure will decrease.
4. The pressure of the gas is not affected by the volume.

39. A system of 3 frictionless pulleys is arranged to lift an object. The arrangement has a Mechanical Advantage of 3. Which of the following statements is false:

1. The force needed to lift the object with the pulleys is one third that needed without them.
2. The work done with the pulleys is no more and no less than that needed without them.
3. The pulleys work because the tension in the rope doubles after it passes each pulley.
4. The distance I move the new force through is greater than the distance the object moves.

40. Which of the following statements about static electricity is false:

1. Static build up can be less on a rainy day as moisture in the air slowly conducts charge away from charged bodies.
2. A positive static charge will strongly attract negative charges and weakly attract neutral charges.
3. Static electricity is the result of a local imbalance in the number of negative and positive charges in substance.
4. Static electricity is the only form of electricity that does not involve electrons.