Measuring Motion What is motion?

Bellringer In your notebook write down if you think you are currently in motion. Please explain why you feel as though you are or are not.

Objectives Describe the motion of an object by the position of the object in relation to a reference point. Identify the two factors that determine speed. Explain the difference between speed and velocity Analyze the relationship between velocity and acceleration. Demonstrate that changes in motion can be measured and represented on a graph.

Reference Point Motion is an object’s change in position relative to another object, or reference point. The object that appears to stay in place is called a reference point. The direction of an object’s motion can be described with a reference direction, such as north, south, east, west, up, or down. Common Reference Points The Earth’s surface, Tree, Building

What is Speed? Speed is the amount of distance traveled divided by the time it took to get there. Units are typically in m/s (SI units) however it can be any unit of distance over time Distance Time Speed =

Average vs. Instantaneous Average Speed The average speed is calculated by the total distance divided by the total time it took to get there. Instantaneous Speed The instantaneous speed is calculated by the current distance traveled by the current time it took to get there. Examples

Graphing Speed

Your try Set up the following questions in your notebook. (you do not need to solve them). Be sure to include units. A cat walked 5 m in 1s. What is the cat’s speed? You can walk 100, in 60s. What is your speed? The mall is 5000m away and takes you 15 minutes (900s). What is the average speed it takes to get to the mall?

If I told you that both my friend and I were walking 5m/s, Velocity vs. Speed If I told you that both my friend and I were walking 5m/s, Are we walking at the same speed? Are we walking at the same velocity? Are they the same?

Velocity is an objects speed in a given direction. In order to be a velocity there must be a reference direction.

If I told you that both my friend and I were walking 5m/s, Think Again If I told you that both my friend and I were walking 5m/s, Are we walking at the same speed? Are we walking at the same velocity? If my friend is walking South and I am walking North our speeds are the same but our velocity is different.?

Resultant Velocity Changing Velocity You can think of velocity as the rate of change of an object’s position. An object’s velocity is constant only if its speed and direction don’t change. Combining Velocities You can combine different velocities to find the resultant velocity. The next slide shows how you can combine velocities to find the resultant velocity.

Calculate Jane is at Universal Studios. She normally travels north at 3 m/s. If she gets on a “moving sidewalk” that travels at 2 m/s north and walks on it, what will be her resultant velocity? 5m/s North Joe is at Universal Studios. He normally travels north at 3 m/s. If he got on a “moving sidewalk” for fun that travels at 2 m/s south and walks on it, what will be his resultant velocity? 1m/s North

In pairs answer the following questions in your notebook: Think Pair Share In pairs answer the following questions in your notebook: If a car travels 400m in 20 seconds how fast is it going? How much time will it take for a bug to travel 5 meters across the floor if it is traveling at 1 m/s? How far can your little brother get if he can travel at 2.5 m/s and in 5 seconds you will discover that his squirt gun has run out of paint?

Answers 400m/2s = 200m/s 5m÷1m/s = 5s 2.5m/s * 5s = 12.5m

What is the difference between speed and velocity? Review What is the difference between speed and velocity? What two things are needed to determine speed?