Exam 4: Gravity and Orbits

How fast is the Moon moving as it orbits Earth? For reference, the Moon's orbit is approximately circular with a radius equal to 400,000 km, and the Moon's orbital period is 27 days.

Newton's law of gravitation says that gravity is a mutually attractive force.Explain the following observation: A small object is dropped on Earth and we see it fall toward Earth.However, we do not observe Earth moving toward the object.

How might tidal forces affect the ability of a planet to sustain life? Provide at least two examples and justify each.

Earth's tidal bulge "leads" the Moon in its orbit.Does this have any effect on the Moon?

According to the scales shown in the figure below, about how many times stronger is gravity on Earth than on the Moon?

Uniform circular motion applies to which of the following orbits?

Mercury orbits the Sun with an average distance of 0.4 AU, and its mass is 0.06 times that of Earth.The gravitational force that the Sun exerts on Mercury is approximately ________ times the force of gravity that the Sun exerts on Earth.

You discover a moon orbiting a planet.The moon has an orbital period of three weeks, and the average distance between the moon and planet is 1.2 *10⁶ km.What is the planet's mass? Compare its mass to that of Jupiter, which is 1.9 * 10²⁷ kg.

The force of gravity that an object has is directly proportional to its

The distance used in Newton's law of gravitation is

If you weighed 150 lb on Earth, what would you weigh on Mars? For reference, Mars has a mass that is 0.1 times Earth's mass and Mars has a radius that is 0.5 times Earth's radius.

Explain the difference between being weightless and being in free fall.

If a person having mass, M, is standing on the ground and experiencing an acceleration due to gravity of g, what is the correct formula for the person's weight, F?

Which of the following properties of an astronaut changes when he or she is standing on the Moon, relative to when the astronaut is standing on Earth?

In the absence of air friction, a 0.001-kg piece of paper and a 0.1-kg notebook are dropped from the same height and allowed to fall to the ground.How do their accelerations compare?

Consider the figure below, which illustrates the tidal bulge on Earth's oceans due to the Moon and four people at different longitudes on Earth from the point of view of an observer looking down on the North Pole of Earth.If you were to arrive at the beach and find that the Moon was visible in the western half of the sky, then is the tide most likely to be coming in and the water level rising; or is the tide going out and the water level going down? Explain the rationale for your answer.

According to the figure below, when Earth is in between the Moon and the Sun, ________ tides occur.

Consider the figure below, which illustrates the tidal bulge on Earth's oceans due to the Moon and Sun from an observer looking down on the North Pole of Earth.At what phase of the Moon will the mildest tides of the month occur? Explain the rationale for your answer either in words or with a sketch.

Tidal forces are caused by

Imagine a planet in a very eccentric elliptical orbit around a star.This planet has no moons, but it has oceans.This planet's orbit is not tidally locked.Are there tides? If so, explain how they would behave.