AP®︎ Physics 1: Topic 2.6 Practice Test

Essential Knowledge: 2.6.A.1

Newton’s law of universal gravitation describes the gravitational force between two objects or systems as directly proportional to each of their masses and inversely proportional to the square of the distance between the systems’ centers of mass. Relevant equation: $\left|\vec{F}_g\right| = G\frac{m_1m_2}{r^2}$

Essential Knowledge: 2.6.A.1.i

The gravitational force is attractive.

Essential Knowledge: 2.6.A.1.ii

The gravitational force is always exerted along the line connecting the centers of mass of the two interacting systems.

Essential Knowledge: 2.6.A.1.iii

The gravitational force on a system can be considered to be exerted on the system’s center of mass.

Essential Knowledge: 2.6.A.2

A field models the effects of a noncontact force exerted on an object at various positions in space.

Essential Knowledge: 2.6.A.2.i

The magnitude of the gravitational field created by a system of mass $M$ at a point in space is equal to the ratio of the gravitational force exerted by the system on a test object of mass $m$ to the mass of the test object. Derived equation: $\left|\vec{g}\right| = \frac{\left|\vec{F}_g\right|}{m} = G\frac{M}{r^2}$

Essential Knowledge: 2.6.A.2.ii

If the gravitational force is the only force exerted on an object, the observed acceleration of the object (in $\mathrm{m/s^2}$) is numerically equal to the magnitude of the gravitational field strength (in $\mathrm{N/kg}$) at that location.

Essential Knowledge: 2.6.A.3

The gravitational force exerted by an astronomical body on a relatively small nearby object is called weight. Derived Equation: $\text{Weight} = F_g = mg$

Essential Knowledge: 2.6.B.1

If the gravitational force between two systems’ centers of mass has a negligible change as the relative position of the two systems changes, the gravitational force can be considered constant at all points between the initial and final positions of the systems.

Essential Knowledge: 2.6.B.2

Near the surface of Earth, the strength of the gravitational field is $g \approx 10\ \mathrm{N/kg}$

Essential Knowledge: 2.6.C.1

The magnitude of the apparent weight of a system is the magnitude of the normal force exerted on the system.

Essential Knowledge: 2.6.C.2

If the system is accelerating, the apparent weight of the system is not equal to the magnitude of the gravitational force exerted on the system.

Essential Knowledge: 2.6.C.3

A system appears weightless when there are no forces exerted on the system or when the force of gravity is the only force exerted on the system.

Essential Knowledge: 2.6.C.4

The equivalence principle states that an observer in a noninertial reference frame is unable to distinguish between an object’s apparent weight and the gravitational force exerted on the object by a gravitational field.

Essential Knowledge: 2.6.D.1

Objects have inertial mass, or inertia, a property that determines how much an object’s motion resists changes when interacting with another object.

Essential Knowledge: 2.6.D.2

Gravitational mass is related to the force of attraction between two systems with mass.

Essential Knowledge: 2.6.D.3

Inertial mass and gravitational mass have been experimentally verified to be equivalent.