Return to Physics IndexAcceleration

Oldenburg, Albert Lindblom Tech High School

471-8700

Objectives:

To develop an understanding of velocity and to distinguish it from

speed. To learn to determine the difference between a scalar and a

vector quantity. To learn how acceleration is derived from velocity

and time.Materials:

Pencil, paper, adding machine tape, 1-ft x 4-ft brown cardboard, 3-ft x

3-ft brown cardboard, marking pens, paste, stick-paste, 8-ft aluminum

u-angle rail, 1/2-lb ball bearing, assorted small wood blocks, assorted

pieces of cardboard as shims, mechanical or electric metronome.Strategy:Since this lesson follows a number of other already in sequence it is assumed that the student has a certain background knowledge necessary for this lesson on acceleration. The student is reminded of certain concepts and introduced to a few new ones. The equipment is set up before class starts. The 8-ft rails are set up with one end propped up about 2 to 3 cm higher than the other so when the steel bearing is allowed to roll down the track it would take about 10 sec to roll from one end to the other. Now we start the metronome and we make a few trial runs. Then we tape a long piece of adding machine tape parallel to the rail. We mark a line on the tape next to where the center of the ball is and also put a 0 on this line. This will be our starting point for our marks. Now we start the metronome and set it for 96 clicks per minute. Then we take a marker and make a countdown starting from 3 to 0 and when at 0 we start marking until we get up to 11 or when the ball reaches the end of the rail. Then we take the tapes and cut them at each mark. After three students ran their tapes and cut them at each mark, we are now ready for the graphing. For graph one we will plot distance vs time. Each person in the group will use his tape for a different graph. He will then decide who will use his tape and for which one (graph). Take the cut tapes and label them d_{1}, d_{2}, d_{3}, etc. Take the first tape and paste it on the

lower left corner vertically of the cardboard graphs we prepared

yesterday. Then take the second (d_{2}) tape and paste it with its lower

left corner next to the upper right corner of the first piece. And

continue pasting each successive strip until you get to the top of the

graph or you get all ten strips pasted.

To do graph two the second person of each group will label their

tape pieces V_{1}, V_{2}, V_{3}, etc. This graph plots V vs t. Paste each strip

vertically starting on the bottom line of the graph and next to each

other. All ten strips should fit on your graph.

Graph three plots change in velocity vs time. Cut and label the

tapes V_{1}, V_{2}, V_{3}, etc. Then lay tape V_{9}on top of V_{10}and cut off the

difference. Call this delta V_{10}. Likewise place V_{9}on V_{8}and cut off

the difference of V_{9}. Then do the rest of the tapes in decending order

until all delta pieces have been cut. Then paste each delta piece from

left to right on the bottom line of the graph.Recordings:After the three graphs from your group are done, you may help other groups to finish. Then measure each tape (in cm.), write these values on each tape and record them in a data table for each student. After all this the class will analyze the graphs and develop a consensus for our conclusion.