Motion, Speed, and Velocity Physics Motion, Speed, and Velocity

SC Standards Covered PS-5.1 PS – 5.2 PS – 5.6 Explain the relationship among distance, time, direction, and the velocity of an object PS – 5.2 Use the formula v=d/t to solve problems related to average speed or velocity PS – 5.6 Represent linear motion of objects on distance – time graphs

Motion When an object changes its position, motion has occurred. Distance- How far an object has moved. Displacement- How far an object has moved in relation to its starting point. Consider direction Example: Two runners travel along the same straight path in a straight line for 500 meters. At the end of the run their distances are the same but their displacements are different. How can this be so?

Speed- Distance an object travels per unit of time Relationships between speed, distance, and time: Speed = Distance/ Time = d/ t Constant Speed- speed does not change over time Average Speed- speed of motion when speed is changing Avg Speed = Total Distance/ Total Time Instantaneous Speed- speed at any given moment in time (speedometer)

Graphing Motion Graph distance on the y-axis and time on the x-axis Slope = rise = distance = speed run time

Distance - Time Graph If something is not moving, a horizontal line is drawn. If something starts out slow and then speeds up, its change in speed can look like this.

Learning Checkpoint This graph shows several stages of motion: Stage 1: 100 m in 10 s Stage 2: 50 m in 10 s Stage 3: 150 m in 20 s Calculate the speed as indicated by each of the colors. Calculate the average speed. What is the total distance? What is the displacement?

Solution Stage 1: S= d/ t 100 m/ 10 s= 10 m/s Stage 2: S= d/t Ave Speed= Tot d/ Tot t 300 m/ 40 s= 7.5 m/s Distance = 300 meters Displacement = 0 meters

Velocity The speed and direction of an object’s motion. 88 km / hr southwest