Motion, Speed, Velocity and Acceleration

• An object is in motion when its distance from a reference point is changing.
• Speed can be calculated if you know the distance and time
• Speed in a given direction is velocity.
• Acceleration refers to the rate of change in velocity of an object.
• An object's motion is a continuous change in position with respect to a reference point for a particular time interval.

Formulas

• Speed equals Distance divided by Time.
• Time equals Distance divided by Speed.
• Distance equals Speed multiplied by Time.
• Velocity equals Distance divided by Time.
• Time equals Distance divided by Velocity.
• Distance equals Time multiplied by Velocity.
• Acceleration equals Velocity divided by Time.
• Time equals Velocity divided by Acceleration.
• Velocity equals Time multiplied by Acceleration.

Diagrams

• Diagrams use pictures or symbols to illustrate and explain an idea or information.

Ticker Tape Diagram/Dot Diagram

• A trail of dots represents the object's motion.
• The distance between the dots represents the speed of the object at a certain time interval.
• A large distance between dots indicates the object moved fast.
• A small distance between dots indicates the object moved slowly.
• Equal distance means constant speed/constant velocity; there is no acceleration.
• Increasing distance between dots means the speed of the object is increasing.
• Decreasing distance between dots means the speed of the object is decreasing.
• Changing speed (changing distance between the dots) means there is acceleration.
• Constant speed is equal to no acceleration.
• Slowing down is decelerating.
• Very fast motion equals to Lots of acceleration.

Illustration of Renatta's motion

• The motion of Renatta Oyle's car is analyzed based on traces of oil left on the street
• Renatta decelerates from a high speed to low speed until she is finally stopped; she remains at rest for a while, then gradually accelerates until the trace ends.
• Renatta travels at a constant speed during the first-time interval and then gradually accelerates until the trace ends.
• Renatta moves with a constant speed in the first time interval, then abruptly decelerates to a stop; she remains at rest for sometime and then moves with a constant speed, slower than the first speed.

Motion Graphs

• Motion graphs are a visual representation that uses lines to show how two or more sets of measurements relate to each other.

Distance-Time Graph

• A distance-time graph determines the change in the position of the object
• A distance-time graph tells the journey of an object.

Analyzing Distance-Time Graphs

• When the distance is not changing on a distance-time graph and appears as a flat, horizontal line, it means the object is at rest.
• Constant speed on the distance-time graph is a straight line that increases in distance over a given time.
• A steeper line on a motion graph indicates a faster speed.
• A ticker tape diagram (or tape chart) describes motion, representing the position of an object at constant intervals of time with a dot.
• A displacement-time graph displays the relationship between distance and time.
• A velocity-time graph displays the velocity an object travels over time.

Displacement-time graph

• The slope in a graph demonstrates the motion of an object. “steepness of the line”.
• Slope = rise (↑) / run (→) = displacement (d) / change in time (t)
• The different types of slope of motion include constant velocity, constant negative velocity(or opposite direction), and at reset "no motion".
• The slope of the graph in Figure 11a is steeper than that in Figure 11b, therefore this steeper slope indicates a faster velocity.

Check For Understanding (motion graphs)

• Segment 0-A The bus is accelerating since it's speed changes from 0 to 10 m/s in 5s.
• The bus in Segment A-B is moving in constant speed of 10 m/s for 5s.
• The bus in Segment B-C is decelerating and slowing down from 10 m/s to rest in 3s.
• The bus in Segment C-D is at rest since it has stopped.
• The bus in Segment D-E is accelerating gradually in that timeframe.

Understand the concepts of motion, speed, velocity, and acceleration. Also, learn about how to calculate Speed, Time and Distance. Diagrams use pictures or symbols to illustrate and explain an idea or information.