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51) If Earth had twice its present mass, but the same radius, what would be the value of g?

g would double

52) About how many high tides are there normally each day on an typical ocean beach?

2 per day

53) A woman who weighs 800 N at Earth’s surface stands on top of a very tall ladder so she is one Earth radius above Earth’s surface. How much does she weigh?

800N / 4

54) If the radius of Earth were one half what it is now, and its mass were the same, what would be the value of g?

4 x 9.8 m/s2

55) How can you tell if a gravitational force exists in a region of space?

see number 88

56) Does the earth, the moon, or the sun produce a greater tidal effect on you right now? Why?

earth, the tidal effect is inversely proportional to the distance

57) Compared to the gravitational field on the surface of Earth, the gravitational field well below Earth’s surface is


58) What is the primary cause of ocean tides?

differential gravitational pull on the oceans

59) If the sun were to collapse to form a black hole (quite unlikely), what would happen to the earth?

nothing, strength of gravitational field from Sun would be the same because the mass would be unchanged and the distance is unchanged

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60) Suppose the moon were covered with water and orbited Earth as it now does. In that case how many tidal bulges would the moon have?


61) There are two main processes going on in the sun that keep the sun in existence and shining. What are these processes?

Gravitation and Nuclear Fusion

62) What do gravitational field lines show?

they show the direction of the acceleration due to that field pointing toward the CofM of the object producing the field

63) Does the mass of the moon and earth affect the number of tidal bulges on Earth? Explain.


64) During an eclipse of the sun, when the moon comes between the sun and Earth, how are ocean tides affected? Explain.

Spring tides, higher than normal tides because the tidal effect created by the sun and the moon work together

65) The force of gravity on you is greatest when you are standing where relative to the earth’s surface, on the surface, just above, or just below? Explain.

Just below

66) What is a black hole? Why is it black?

Gravitational field is so strong that light cannot escape

67) What causes Earth tides, in which the solid surface of Earth rises and falls?

Same as ocean tides

68) What is the factor most directly responsible for making a black hole invisible?

Mass concentrated in a very small radius

69) Suppose the moon had twice its present mass and still orbited Earth at the same distance. In that case what would happen to ocean tides? Would the tidal bulge facing away from the moon get smaller?

Tides would get larger. No

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70) If the mass of the earth increased, with no change in radius, what would happen to your weight?

change proportionally to the increase in mass

71) What causes a lunar eclipse? Explain completely.

Earth casts its shadow on the moon

72) The value of the acceleration due to gravity, g, is dependent upon what variables?

g= F/m = GM/R2 , depends on mass and distance

73) What causes a solar eclipse? Explain completely.

Moon gets between observer on earth and the sun

74) When a star collapses to form a black hole, what happens to its mass?


75) What is the gravitational field strength at the center of the Earth?

net strength is zero

76) Are tides more likely to occur on a large planet or a small planet? Why?

large, greater differential gravitational pull

77) According to Newton’s laws, a rock and a pebble will fall with the same acceleration in a gravitational field even though the gravitational force on each is different. Explain why this is possible.

acceleration is always the same.

78) If you were to weigh yourself in an elevator that is accelerating upward, would your weight be greater or less than normal? Explain why.

as long as it is accelerating, you would weigh more on the scale

79) Gravitation weakens as the inverse square of distance, while tidal gravity (force per kilogram) weakens with the inverse

cube or third power


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80) If you drop a stone into a hole drilled all the way to the other side of Earth, describe the motion of the stone. Where will it be moving fastest?

81) If the radius of the earth decreased, with no change in mass, what would happen to your weight?

82) Which pulls harder on Earth’s oceans, the sun or the moon?

83) When the moon’s shadow falls on Earth, what kind of eclipse occurs?

84) When Earth’s shadow falls on the moon, what kind of eclipse occurs?

85) What defines a spring tide?

86) If the moon had oceans as deep as Earth’s, would tides on the moon be about the same height as Earth’s tides?

87) What is the cause of ocean tides? Be complete in your explanation.

88) When the properties of space are altered in such a way that a mass in that space experiences a force, what kind of field is present?

89) What variables determine the acceleration due to gravity?

90) Does a skydiver jumping from a plane in the direction of the Earth’s gravitational field, or in a direction opposite that field?

91) What is it about the Earth that gives it a gravitational field?

92) What defines a neap tide?.

93) If Earth had its present mass but twice the radius, what would happen to the acceleration due to gravity?

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Copyright © 2005 -  S. B. EglI