Sunshine State Standard

SC.C.1.3.1

Materials

1. Board, 3/4 x 12" x 6' 2. Blocks of wood (Approx 2"x4"x12") 3. Stop watch 4. Masking tape 5. Tape measure, 25' 6. Smooth working area 1. Board, 3/4 x 12" x 6' 2. Blocks of wood (Approx 2"x4"x12") 3. Stop watch 4. Masking tape 5. Tape measure, 25' 6. Smooth working area

What to do

Objective: The Learner Will be able to calculate the average speed of a rolling object. Introduction: Discuss the definitions of speed, velocity, and acceleration as explained in prior lessons. Speed = distance /time Speed is identified as the unit of distance measurement (miles, feet, revolutions, etc.) per unit of time measurement (seconds, minutes, hours, days, etc.). For example: If a person walks three miles in four hours, you would divide the distance (4 miles) by the time (3 hours) {4 /3 = 1.333}. Therefore the person walked the distance at an average speed of 1.333 miles per hour. Use additional examples as needed for clarification. Explain that the class will be using a bowling ball, a ramp (inclined plane), tape, stop watch, notebook, and a calculator. The class will be divided up into teams of 4, and each team will have a timer, ball-controller, spotter, and ball chaser. Procedure: (Demonstrate on chalk board or overhead) The ball will be leased from the top of the inclined pane when the timer is ready and says "GO" and starts the stop watch. When the ball crosses the tape that was put down at 20 feet (distance is adjustable) from the starting point the spotter says, "STOP", and the timer stops the stop watch. The ball chaser retrieves the ball, and the recorder records the time given by the timer. Repeat this procedure for a minimum of three times in order to obtain a good average time. Add the recorded times together, and then divide the sum by the number of times added. Example: If the following times were recorded: 10.3, 11.5, 9.8, and 10.1; add them together and the sum is 40.7. Divide 40.7 by 4, and the answer 10.175, is then divided into 20feet. 20 /10.175 = 1.966 feet per second. Therefore, the average speed of the ball rolling from this inclined plane was 1.966 feet per second. -------------------------------------------------------------------------------- What would the average speed be if the measured distance was shorter? Longer? -------------------------------------------------------------------------------- Would the average speed increase if the angle of the ramp (height) was increased? -------------------------------------------------------------------------------- What would happen if the ramp was made shorter?? Or longer??

Additional Information

Good activity to expand on this lesson can be found at http://www.marshfield.coos-bay.k12.or.us/Academics/AppliedMath/prob4.htm

Submitted by

William (Bill) Buhler

LaBelle County
Hendry, Florida
buhler_b@popmail.firn.edu