Gravity on a Roll Gravity Rules And Gravity

Gravity on a Roll Gravity Rules! And Gravity Always Wins

Engage What will happen … if you drop this heavy book and a sheet of paper from the same height? What would Aristotle say? What would Galileo say? What do you say?

Explore Marble/Steely Race Materials: track (two yard sticks taped to form a groove) marble steely stopwatch metric tape graph paper calculator

Explore Marble/Steely Race Reading a ruler and stopwatch.

Explore Marble/Steely Ball Race I: a closer look? Procedure Outline: 1) Construct and set up track. 2) Assign jobs (teams of 4). 3) Measure and record ball mass. 4) Predict the relation between the times for two balls of different mass to travel the same distance (a little less than a meter). 5) Measure and record for each ball.

Explain Marble/Steely Ball Race: Discussion 1. Compare data – any pattern? 2. What is the problem? 3. Precision - Reaction time 3. How can we fix this? More trials – Average 4. Aristotle vs. Galileo.

Explain Newton’s Second Law of Motion Any force acting on an object will change its motion. ► How much change there is depends on the object’s mass and applied force. ►

Explain Speed, Velocity, Acceleration Speed: how fast something is going; average speed is measured by the distance traveled divided by the time needed to travel that distance Velocity: the speed and direction something is moving Acceleration: any change in motion of an object; a change in direction and/or speed

Explore Marble/Steely Ball Race II: a closer look? Procedure Outline: 1) Predict the motion: Sketch a position vs. time graph like you did for the trip to Grandma’s house. 2) Measure and record the position at every second. 3) Plot position vs. time. 4) Calculate the average speed for each time interval (distance traveled / time taken – recall facet 40). 5) Plot average speed vs. time – pattern?

Explain Newton’s Second Law of Motion Any force acting on an object will change its motion. ► How much change there is depends on the object’s mass and applied force. ►

Extend Take better measurements. How could you take better measurements? Try a second mass in experiment II. Washers on string

Evaluate 1. Apply the terms speed, velocity, and acceleration to what you observed. 2. Revisit the introductory demonstration and apply the terms speed, velocity, and acceleration to what you observed.

Homework Due 1/23/07 in class H 1: Replot your two sets of data on one sheet of graph paper. The top plot should be position vs. time and the bottom plot should be velocity vs. time. Choose good scales that show the data clearly. 2. On the other side of the graph paper describe what is happening in each graph using the terms on the other side of this sheet. 1. v Remember to do the Diagnoser Set by 6 PM Monday (1/22/07). See the class web page.