# CPS4 - Chapter 4

## 9 terms

### inverse-square law

The intensity of an effect from a localized source spreads uniformly throughout the surrounding space and weakens with the inverse square of the distance.

### weight

the force that an object exerts on a supporting surface (or, if suspended, on a supporting string), which is often, but not always, due to the force of gravity.

### weightless

having little or no weight or apparent gravitational pull

### Law of universal gravitation

Every body in the universe attracts every other body with a force that, for two bodies, is directly proportional to the product of their masses and inversely proportional to the square of the distance separating them.

### Projectile

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

### Parabola

The curved path followed by a projectile under the influence of constant gravity only.

### Satellite

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

### Ellipse

The oval path followed by a satellite

### Escape Speed

The speed that a projectile, space probe, or similar object must reach to escape the gravitational influence of Earth or of another celestial body to which it is attracted.