Motion of a Bowling Ball

John J. Miller                 Maine Township High School East
                               2601 Dempster
                               Park Ridge IL 60068
                               (847) 825-4484

Objectives:

The students will be able to make a distance vs. time graph of a bowling ball 
and have practice reading distance vs. time graphs of various motions. 

Materials:

A bowling ball, 5 - 10 stopwatches, a massive object to let the ball collide 
into and not hurt anyone, white boards (this is a 8 foot by 4 foot sheet of 
white paneling board that can be bought at most big hardware stores and is cut 
into 1 foot x 1 foot boards), dry erase markers, and paper towels to clean off 
the boards. 

Strategies:

Phase 1: 
This is a Socratic/phenomenological form of questioning to do a lab.  One of the 
"hidden" purposes to this lab is to get away from the standard, cookbook forms 
of the lab manual, and have the students make the plan of attack with small 
prompts from the teacher.  I will repeat, you want to get away from the "now 
we'll do this" and move toward the "What do we need to do in order to make a 
distance vs. time graph of a bowling ball as it rolls?" 

In your mind, you know you want to have the students line at equally spaced 
distances (for example every five feet) in the hall way.  You could be courteous 
with your fellow teachers and warn them a day or two ahead of time.  I think it 
is worth the extra trouble because this is an excellent opportunity to do 
science outside of the classroom - which is an entire other story.  You would 
like stopwatches in there little hands.  You would like the students to all 
start there stopwatches when you roll the bowling ball slowly.  When the ball 
passes them you would like them to stop their stop watches.  You would like 
someone to collect the data in a column form so that you can make another trial 
rolling the ball faster.  You would like them to go into the classroom and graph 
the data (distance on the vertical axis and time on the horizontal axis).  You 
can them ask questions such as "What do you notice about the best fit lines of 
the two trials?"  Hopefully you will get the faster trial is steeper and the 
slower trial is less steep. 

Now is a good time to regroup and explain that if the line is horizontal it 
means the object is stopped and the slope of the line (steepness) tells the 
speed.  

Phase 2
Hand out the white boards and dry erase markers and a paper towel to clean them 
off.  Explain to the students you are going to walk across the front of the 
class room and you would like them to make a sketch of a distance vs time graph 
(qualitative graph) of your motion.  The following are some suggested motions to 
walk in order to have the students build from simple to more complicated. 

a) walk at a constant speed 
b) walk at a constant speed, stop for a time and walk at the original speed 
c) walk at a constant speed, stop for a time and walk at a speed faster 
   than the original speed 
d) walk slow and then speed up 
e) walk fast and then slow down 
f) walk forward at a constant speed and then back toward the origin 

Phase 3:
Have two students come up to the front of the class room.  Have one student make 
a distance vs. time graph but not show anyone except the other student in front.  
He will try to walk like the sketch the first student made and the rest of the 
students will make a sketch of how the walking student walked.  Compare the 
original sketch made by the first student 

Performance Assessment:

Walk some method and have the students make a distance vs. time graph of your 
motion. 

Conclusions:

On a distance vs. time graph the slope (steepness) of the line tells you about 
the speed of the object.  The larger the slope (steeper the line) the faster the 
object travels.  The smaller the slope (the less steep the line), the slower the 
object.  A flat line means the object has stopped. 

References:
Me: Give me a call.