# Ch.1 - Motion and Momentum

## 15 terms

### speed

the distance traveled divided by the time it takes to travel that distance

### average speed

the total distance traveled divided by the total time taken to travel the distance

### instantaneous speed

the speed of an object at one moment in time

### velocity

speed and direction of a moving object

### positive acceleration

when acceleration is in the direction an object is moving

### inertia

tendency of an object to resist a change in its motion

### momentum

a measure of how hard it is to stop a moving object; dependent on the object's size and velocity

### law of conservation of momentum

the total momentum of objects that collide with each other is the same before and after the collision

### motion

a change in position

### distance

how far an object moves

### displacement

how far an object moves relative to its starting point

### relative motion

a change in position of one object compared to the position of another

### negative acceleration

when acceleration is against the direction an object is moving

### collision

when two or more objects hit each other

### acceleration

the change in velocity divided by the time for the change to take place; occurs when an object speeds up, slows down, or turns