Acceleration

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 d1, d2, d3, 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 (d2) 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 V1, V2, V3, 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 V1, V2, V3, etc.  Then lay tape V9 on top of V10 and cut off the 
difference.  Call this delta V10.  Likewise place V9 on V8 and cut off 
the difference of V9.  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.