Ch4 Gravity, Projectiles, and Satellites

Universal Law of Gravity

Every body in the universe attracts every other body with a mutually attracting force.

Inverse-Square Law

Describes how the intensity of an effect is inversely proportional to the square of the distance from the cause.

Weight

The gravitational force exerted on an object by the nearest most massive body.

Weightlessness

A condition where a support force is lacking, such as in free fall.

Projectile

Any object that moves through the air or space under the influence of gravity.

Parabola

The curved path followed by a projectile near the Earth under the influence of gravity.

Satellite

A projectile or small celestial body that orbits a larger celestial body.

Escape Speed

The initial speed that an object must reach to escape the gravitational influence of Earth.

Elliptical Orbit

The closed path followed by a satellite that is not circular, varying in distance from the body it orbits.

Tangential Velocity

The horizontal velocity required for a projectile to maintain a circular orbit around a celestial body.

Escape Velocity

The minimum speed required for a projectile to break free from a celestial body's gravitational pull.

Gravitational Constant (G)

The proportionality constant in the equation of universal gravitation, approximately equal to 6.67 × 10⁻¹¹ N·m²/kg².

Newton's Law of Universal Gravitation

The force of gravitational attraction between two objects is proportional to the product of their masses and inversely proportional to the square of their distance apart.

Free Fall

The motion of an object where gravity is the only force acting on it.

Tangential Velocity

The velocity of an object moving along a curved path, tangent to the curve at the point of interest.

Centripetal Force

The force that keeps an object moving in a circular path, directed toward the center around which the object is moving.