Physics Quiz: Planetary Motion

What is the fundamental force that explains why objects fall at the same rate and why objects in space are naturally attracted to one another?

• Strong nuclear force

• Gravitational force

• Electromagnetic force

• Weak nuclear force

According to Newton's law of gravitation, the strength of the gravitational force is directly proportional to which of the following?

• Mass of the objects

• Temperature of the objects

• Velocity of the objects

• Distance between the objects

What is the region around a massive object where other objects with mass would experience an attractive force called?

• Magnetic field

• Electric field

• Gravitational field

• Centripetal field

Which of Kepler's laws states that all planets move about the Sun in elliptical orbits, having the Sun as one of the foci?

• First Law

• Second Law

• Third Law

• Fourth Law

Kepler's Second Law states that the radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time. What does this imply about the speed of planets along their orbits?

• Variable speed

• No speed

• Constant speed

• Opposite speed

According to Kepler's Third Law, what is directly proportional to the cube of the average distance of a planet from the Sun?

• Orbital period

• Mass of the planet

• Temperature of the planet

• Size of the planet

What is the acceleration directed toward the center of a circular path called?

• Tangential acceleration

• Radial acceleration

• Centrifugal acceleration

• Centripetal acceleration

In the context of planetary motion, what is the semi-major axis of an elliptical orbit?

• Radius of the orbit

• Half of the longest diameter of the ellipse

• Distance from the Sun to the planet

• Distance from the Earth to the Moon

How does the strength of the gravitational field change as the mass of an object increases?

• Increases

• Decreases

• Remains constant

• Becomes zero

What is the relationship between the squares of the orbital periods of planets and the cubes of their semi-major axes according to Kepler's Third Law?

• Directly proportional

• Inversely proportional

• No relationship

• Random relationship