# Gravity and Gravitation - Key terms

### FORCE:

The product of mass multiplied by acceleration.

### FRICTION:

The force that resists motion when the surface of one object comes into contact with the surface of another.

### INERTIA:

The tendency of an object in motion to remain in motion, and of an object at rest to remain at rest.

### INVERSE RELATIONSHIP:

A situation involving two variables, in which one of the two increases in direct proportion to the decrease in the other.

### LAW OF UNIVERSAL GRAVITATION:

A principle, put forth by Sir Isaac Newton (1642-1727), which states that every object in the universe attracts every other one with a force proportional to the masses of each, and inversely proportional to the square of the distance between them.

### MASS:

A measure of inertia, indicating the resistance of an object to a change in itsmotion.

### TERMINAL VELOCITY:

A term describing the rate of fall for an object experiencing the drag force of air resistance. In a vacuum, the object would continue to accelerate with the force of gravity, but in most real-world situations, air resistance creates a powerful drag force that causes a leveling in the object's rate off all.

### VACUUM:

Space entirely devoid of matter, including air.

### WEIGHT:

A measure of the gravitational force on an object; the product of mass multiplied by the acceleration due to gravity.

## User Contributions:

Abbey
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