Gravitational constant

Definition

The gravitational constant, denoted as $G$, is a fundamental physical constant that quantifies the strength of gravitational attraction between masses. Its value is approximately $6.67430 \times 10^{-11} \, m^3 kg^{-1} s^{-2}$.

5 Must Know Facts For Your Next Test

1. The gravitational constant $G$ appears in Newton's Universal Law of Gravitation: $F = \frac{Gm_1m_2}{r^2}$.
2. $G$ has a very small numerical value, reflecting the relative weakness of gravitational force compared to other fundamental forces.
3. The units of $G$ are $m^3 kg^{-1} s^{-2}$, which can be derived from the equation used in calculating gravitational force.
4. $G$ was first measured by Henry Cavendish in 1798 using a torsion balance experiment.
5. Accurate knowledge of $G$ is crucial for calculations involving planetary motions and satellite trajectories.

Review Questions

• What role does the gravitational constant play in Newton's Universal Law of Gravitation?
• How was the value of the gravitational constant first determined?
• Why is the numerical value of the gravitational constant considered to be very small?

Related terms

Newton's Universal Law of Gravitation:

A law stating that every point mass attracts every other point mass by a force acting along the line intersecting both points; this force is proportional to the product of their masses and inversely proportional to the square of the distance between them.

Torsion Balance: A device used to measure very small forces by observing their effect on a system suspended from a wire or fiber that twists under torque.

Centripetal Force: A force that acts on an object moving in a circular path, directed toward the center around which the object is moving.