Dr C. Barnbaum
SAMPLE SECOND MIDTERM EXAM
____ 1. Which is NOT electromagnetic radiation?
d) gamma ray
____ 2. Which is arranged in order of decreasing energy?
a) x-ray, uv, infrared, radio
b) uv, visible, radio, infrared
c) gamma rays, uv, infrared, visible
d) x-rays, visible, uv, radio
e) radio, visible, x-rays, gamma rays
____ 3. Which of the following scenarios for the origin of the solar system best fits our present-day observations of the Sun and planets? The planets formed when they
a) condensed from parts of a cloud of gas orbiting the new Sun
b) were pulled out of the Sun by a passing star
c) were captured by the Sun from a passing star
d) were thrown out from the Sun as it was spinning
____ 4. Which of the following is NOT true about the solar system when it was forming?
a) the Sun formed much later than the planets
b) the cloud that formed the solar system was made of gas and dust
c) the cloud that was to form the solar system collapsed under its own gravity
d) the center of the cloud spun faster and faster as more mass collected in the center
____ 5. Two important things happen when an object that is initially spread out (like a large cloud in space) starts to concentrate its mass at the center (collapse). It will
a) merge its mass and disappear from the universe
b) stop all rotation and become very cold
c) spin more slowly and puff into a sphere
d) spin faster and flatten
____ 6. The inner planets are all rocky and relatively small whereas the outer planets are comparatively huge and made mostly of gas. Why?
a) the inner solar system was so hot that solid material like iron and silicates melted together
b) the outer solar system was too cold to form sticky ices
c) the inner solar system was too hot to form sticky ices
d) it happened that way completely by chance
____ 7. Electromagnetic radiation
a) travels with infinite speed
b) travels more slowly than sound
c) is defined as something we cannot see
d) cannot travel through a vacuum
e) sometimes behaves as a wave and sometimes as a particle
____ 8. Compare two light waves, one of short wavelength and the other with a longer wavelength. The one with the shorter wavelength has
a) a longer life
b) a higher frequency
c) a lower energy
d) a lower frequency
____ 9. The force of gravity between two bodies depends on
a) the mass of both bodies and their separation
b) the mass of one of the bodies only
c) the separation of the bodies only
d) only the universal constant of gravitation, G
e) the acceleration of the planet
____ 10. To escape the gravitational force of the planet Earth, you must achieve a
a) certain minimum acceleration
b) certain minimum velocity
c) certain minimum orbit
d) certain minimum angle
e) nothing--you can never escape from the Earth gravitational force
____ 11. To launch a feather and a rocket to the planet Mars successfully, what must be true?
a) the feather must have a larger escape velocity than the rocket
b) the rocket must have a larger escape velocity than the feather
c) the feather and the rocket must each have reached the same escape velocity
d) the same force must be used on both the feather and the rocket to achieve the escape velocity needed
____ 12. When you attach a rock to a rope and swing it over your head in a circle, the rock is being accelerated toward your hand. If the rope suddenly breaks, the rock will
a) travel in a straight line away from you and eventually land on the floor
b) continue to go in a circle around your hand
c) will drop straight down on the floor
____ 13. What provides the acceleration of the space shuttle so that it orbits the Earth?
a) the force of gravity between the astronauts and the space shuttle
b) the electromagnetic force between the Earth and the space shuttle
c) the force of gravity between the Earth and the space shuttle
d) the shuttle accelerates itself by burning fuel to remain in orbit
e) the shuttle has a constant orbital speed, so it is not being accelerated
____ 14. Is there a gravitational force between the Earth and an astronaut in the space shuttle as it orbits the Earth?
a) no, she is weightless
b) yes, but she doesn't feel it because she is in free-fall
c) yes, and to compensate, the shuttle must pull up on her against gravity
d) no, but she exerts a gravitational force on the Earth
The following equations are useful for answering the next few questions
____ 15. If the Earth's mass were nine times greater than it really is, what would the escape speed be?
a) 2 times larger than normal earth's escape speed
b) 3 times larger than normal earth's escape speed
c) 9 times larger than normal earth's escape speed
d) smaller than than normal earth's escape speed
e) infinite and nothing would escape
f) no change
____ 16. What would be the escape speed for a planet with the same mass as Earth but 4 times the radius of Earth?
a) 2 times the escape speed of Earth
b) 4 times the escape speed of Earth
c) one half the escape speed of Earth
d) 7 miles per second
e) escape would not be possible
____ 17. If you weigh 120 lbs on Earth, what would you weigh on the Moon where the force of gravity is about the force of gravity on Earth?
a) same as my weight on Earth
b) 720 lbs
c) no weight--weightless
d) 20 lbs
____ 18. If you weigh 120 lbs on Earth, what would your MASS be on the moon where the force of gravity is about the force of gravity on Earth?
a) 20 lbs
b) 120 lbs
c) 720 lbs
d) same as on Earth
____ 19. What is the difference between a planet and a star?
a) stars have fusion, planets do not
b) planets have fusion, stars do not
c) stars radiate light, planets do not
d) there is no essential difference
____ 20. The mass of Mars is (Me is the mass of Earth) and its radius is about (Re is the radius of Earth). If you weigh 100 lbs on Earth, how much would you weigh on Mars?
a) 20 lbs
b) 40 lbs
c) 50 lbs
d) same as on Earth
____ 21. Using the values in the question above, what velocity would you need to escape Mars, given that the escape velocity from Earth is 7 miles per second?
a) faster than the escape velocity of Earth
b) slower than the escape velocity of Earth
c) twice as fast than the escape velocity of Earth
d) slower than the escape velocity of Earth
d) same as on Earth
____ 22. You weigh 120 lbs and you are standing on a weight scale inside an elevator on the 50th floor of a skyscraper. If the elevator cable snaps and the brakes fail so that the elevator drops freely, what would the scale say your weight is?
a) 120 lbs
b) 1200 lbs
c) 20 lbs
d) zero lbs
____ 23. Two kids of the same height are throwing balls. One kid throws the ball horizontally with an initial speed of 10 miles/hour. At the exact same instant, the other kid lets the ball fall to Earth by dropping it — with no horizontal velocity. Both balls strike the ground at the same time because
a) both balls have achieved orbital velocity
b) the force of gravity only pulls in a horizontal direction
c) gravity does not affect either ball
d) it is merely a coincidence that the balls land at the same time
e) the force of gravity pulls downward only
____ 24. The temperature of a gas is related to the
a) average speed of the atoms
b) chemical mixture of the gas
c) size of the atoms
d) number of electrons in the atoms of the gas
____ 25. The Sun is mostly hydrogen, but the Earth has no hydrogen in its atmosphere. Why?
a) Earth was hit by so many heavy asteroids early on that the heavy elements out-numbered the hydrogen atoms that were there.
b) Earth formed too far away from the Sun to have hydrogen
c) for the temperature of the Earth, the average velocity of hydrogen is lower than the escape velocity of Earth.
d) for the temperature of the Earth, the average velocity of hydrogen is greater than the escape velocity of Earth.
____ 26. In general terms, a tide is best described as a
a) gravitational distortion
b) rise in the level of the ocean once a day
c) synchronous rotation
d) range of the force of gravity
27. The Moon and the Earth exert tidal forces on each other. In the picture above, draw arrows at points a, b, and c that represent the force of gravity that the moon exerts on the Earth. The stronger the force of gravity at a given point, the longer the arrow should be.
____ 28. The moon is in tidal lock with the Earth. That means that the moon's
a) orbital period cannot be measured
b) rotation is such that we see all sides of the moon during the month of its orbit
c) rotation period is equal to its orbital period around the Earth
d) rotation period is equal to its orbital period around the Sun
____ 29. The ocean bulges out on both sides of the Earth. Why does it bulge on the side away from the moon (side C)? Because the pull of the moon is
a) stronger at C than at A
b) stronger at C than at B
c) weaker A than at B
d) weaker at C than at B
30..In the picture on the left, draw a position of the moon that would cause a spring tide on Earth.
31..In the picture on the left, draw a position of the moon that would cause a neap tide on Earth.
____ 32. The terms neap and spring tides refer to the effect of the relative positions of
a) the Sun and moon
b) the oceans and the continents
c) the Earth and Sun
____ 33. Right now, the Moon takes about 28 days to complete a full orbit around the Earth. If you stood at one location on the Moon, how long would a moon-day take? (that is, how long would it take from sunrise to sunrise?)
a) 365 earth-days
b) 28 hours
c) 28 earth-days
d) 24 hours
____ 34. The ocean tides on Earth occur primarily due to the
a) sun's gravitational pull
b) moon's albedo
c) moon's gravitational pull
d) sun's albedo
e) moon's electromagnetic radiation
____ 35. Ultra-violet light has
a) a lower energy than visible light
b) a higher energy than visible light
c) the same energy than visible light
____ 36. The energy of a light wave depends solely on its
d) electric component
e) magnetic component
____ 37. Which of the following is NOT a property of waves
d) gravititational energy
____ 38. Which of the following is NOT well described by wave motion?
a) cork bobbing up and down on the ocean
b) a book sliding across the table
d) violin string being bowed or plucked
e) ripples on a pond
____ 39. Which of the four fundamental forces is responsible for light?
b) Electromagnetic force
c) Strong force
d) Weak force
____ 40. All objects radiate light. What determines how much light an object radiates at each wavelength?
____ 41. All objects, including people, radiate light. Why can we see each other in daytime, but we can't see each other at in total darkness?
a) we radiate infrared light but do not radiate visible light
b) we radiate visible light which cannot be seen in the dark
c) we only reflect infrared light
____ 42. What is the one fundamental difference between x-rays and radio waves?
a) one is light, the other is sound
b) they come from different sources
c) radio waves are always wave-like, but x-rays always behave like particles
d) their wavelengths are different
e) their speed in outer space is different
____ 43. Where is visible light in the electromagnetic spectrum?
a) between infrared and radio
b) between radio and infrared
c) between ultraviolet and x-rays
d) between ultraviolet and infrared
____ 44. The speed of light in water or in glass is
a) much greater than the speed of light in the vacuum of space
b) less than in the vacuum of space
e) exactly the same as in the vacuum of space since the speed of light cannot vary
____ 45. Why do stars appear to twinkle?
a) because light reflects off of clouds
b) due to diffraction of light through interstellar space
c) due to refraction of light by the turbulent atmosphere of Earth
d) stars themselves are changing in brightness very fast
e) stars are not inherently bright
____ 46. A visible light image of a star shows faint blue light. However, an ultraviolet image shows that the star is much brighter in the ultraviolet. This tells us that
a) the star is very cold since its light is stronger in the visible
b) the star is very hot since its light is stronger in the ultraviolet
c) nothing about the star
d) we cannot know anything from the images about the star
____ 47. A large mirror diameter is desired for telescopes
a) to provide better magnification of the image
b) to collect more light to provide better image resolution
c) to introduce spherical aberration
d) to provide a large field of view
____ 48. A radio telescope dish is a
____ 49. Optical and radio telescopes are alike in that they both use
c) the same type of light detector
____ 50. In general terms, a good mirror needs to be smooth, and how smooth it needs to be depends on
a) the size of the mirror
b) the wavelength of light you observe
c) the manufacturer
d) the temperature at the observatory
____ 51. Optical and radio telescopes differ in what they use for
c) the type of detector
____ 52. Why can't you see yourself when you look in a radio dish ?
a) because a radio dish is not a mirror
b) because a radio dish receives only radio wavelengths
c) because a radio dish isn't smooth enough to be a good visible mirror
d) you can indeed see yourself when you look in a radio dish
____ 53. Which has better resolution?
a) a 4 m radio telescope designed to observe at a wavelength of 2 cm
b) a 4 m optical telescope designed to observe at visible wavelengths
____ 54. An atom is mostly
____ 55. A "quantum" is
a) a discrete value of something, meaning no more and no less than that value
b) a huge change in something
c) a very small change in something
d) an electron's path
e) an electron's charge
____ 56. The Bohr model of the atom is easy to picture but it is fundamentally incorrect. Why?
a) the electron is really much smaller than shown in the Bohr model
b) the nucleus is really much smaller than shown in the Bohr model
c) electrons do not follow fixed paths around the nucleus
d) protons are not alone in the nucleus
____ 57. A better model for the atom than the Bohr model is the electron cloud model. The "cloud" refers to
a) the exact place an electron will be at a given instant with a given energy
b) a probability that the electron of a given energy will be found in the region
c) the stormy, turbulent atmosphere in the atom
d) the softness of the outside of the atom
____ 58. Which of the four fundamental forces is responsible for the fact that you don't fall through the floor and then on through the Earth?
a) electromagnetic force
b) gravitational force
c) weak force
d) strong force