Gravitational Fields _ A-Level Physics

The video tutorial explains gravitational fields, starting with their representation and properties. It covers Newton's law of gravitation, detailing the force between masses and the equation involved. The concept of gravitational field strength is introduced, with a focus on uniform and radial fields. The tutorial then explores planetary motion, highlighting Kepler's third law and its implications for celestial bodies. Finally, it discusses geostationary orbits, their characteristics, and practical applications like TV satellites.

What is the reason for assuming a constant acceleration due to gravity on Earth's surface?

• The gravitational field is non-uniform.

• The gravitational force is weak.

• The field lines are pointing in different directions.

• The change at small vertical heights is negligible.

According to Newton's law of gravitation, what is the relationship between the force and the distance between two masses?

• Inversely proportional to the distance.

• Directly proportional to the square of the distance.

• Inversely proportional to the square of the distance.

• Directly proportional to the distance.

How is gravitational field strength defined in a uniform field?

• Force per unit volume.

• Force per unit mass.

• Force per unit distance.

• Force per unit area.

What does Kepler's third law state about the relationship between the orbital period and the radius of orbit?

• T^3 is directly proportional to R^2.

• T^2 is directly proportional to R^2.

• T^3 is directly proportional to R^3.

• T^2 is directly proportional to R^3.

What is a characteristic of a geostationary orbit?

• It is used for weather satellites.

• It is located above the poles.

• It is always above the same point on Earth's surface.

• It has an orbital period of 12 hours.