Physics Gravity and Gravitation 2

Question 1

Kepler's Second Law (Law of Equal Areas) states that a planet:

Accepted Answer

Sweeps out equal areas in equal time intervals as it orbits

Answer

Kepler's Second Law means a planet moves faster when near the Sun and slower when far away, always sweeping equal areas in equal times.

Question 2

Kepler's Third Law states that the square of a planet's orbital period is proportional to:

Accepted Answer

The cube of its semi-major axis

Answer

Kepler's Third Law: T² ∝ a³, linking the orbital period T to the semi-major axis a of the orbit.

Question 3

Escape velocity is defined as the minimum speed needed to:

Accepted Answer

Break free from a planet's gravitational field without further propulsion

Answer

Escape velocity is the minimum launch speed required to escape a gravitational field entirely, given by v = √(2GM/r).

Question 4

Earth's escape velocity is approximately:

Accepted Answer

11.2 km/s

Answer

Earth's escape velocity is approximately 11.2 km/s, calculated using v = √(2GM/R) with Earth's mass and radius.

Question 5

In free fall, objects of different masses (ignoring air resistance):

Accepted Answer

All accelerate at the same rate g

Answer

In free fall, all objects accelerate at g ≈ 9.8 m/s² regardless of mass, as famously demonstrated by Galileo.

Physics Practice Test