Distance, Displacement & Speed

Distance The length two points

Measuring Distance The SI unit for measuring distance is the meter (m). For very large distances, it is more common to make measurements in kilometers (km). Distances that are smaller than a meter are measured in centimeters (cm).

Displacement Direction from the starting point and the length of a straight line from the starting point to the ending point.

Speed -The ratio of the distance an object moves to the amount of time the object moves. -The SI unit of speed is meters per second (m/s). -Two ways to express the speed of an object are average speed and instantaneous speed.

Formula used to Calculate Speed Speed (m/s)=distance (m) time (s) S=d t

Average Speed The total distance traveled, d, divided by the time, t, it takes to travel that distance.

Instantaneous Speed The rate at which an object is moving at a given moment in time. The speedometer in a car measures the car’s instantaneous speed.

Graphing Motion Speed can also be determined by looking at a distance-time graph. The slope of a line on a distance-time graph is the speed of the object. Slope is the change in the vertical axis value divided by the change in the horizontal axis value. Steeper slope means faster speed.

Distance-Time Graphs

Distance-Time Graphs

Distance-Time Graphs

Velocity Velocity is a description of BOTH speed and direction of motion. The unit for velocity is meters per second (m/s).