Unit 6

AP Physics 1 - Unit 6: Circular Motion and Gravitation

Key Concepts

• Uniform Circular Motion: Motion in a circle at constant speed. Key features include:

  • Centripetal force required to keep object moving in a circle (directed towards the center).

  • Formulas:

    • Centripetal acceleration, (a_c = \frac{v^2}{r}) (where v = tangential speed, r = radius)

    • Centripetal force, (F_c = m \cdot a_c = \frac{mv^2}{r})

• Newton's Law of Universal Gravitation:

  • Every point mass attracts every other point mass with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

  • Equation: (F = G \frac{m_1 m_2}{r^2}) (where G = gravitational constant, (m_1) and (m_2) are the masses, and r is the distance between the centers)

Gravitational Potential Energy

• The energy an object possesses due to its position in a gravitational field.

  • Gravitational potential energy formula: (U = mgh) (where h = height above a reference point).

Orbital Motion

• Objects in orbit experience both gravitational force and centripetal force.

  • For circular orbits, the gravitational force provides the necessary centripetal force to keep an object in orbit.

Important Equations to Remember

• Centripetal acceleration: (a_c = \frac{v^2}{r})

• Centripetal force: (F_c = ma_c = \frac{mv^2}{r})

• Gravitational force: (F = G \frac{m_1 m_2}{r^2})

• Potential energy: (U = mgh)

Examples to Study

• Problems involving objects in circular motion (calculating forces, acceleration, and velocities).

• Gravitational force calculations between two masses.

• Understanding how changes in radius and mass affect gravitational force and acceleration in orbits.