Momentum

Sandra Tucker                  Crown Fine Arts Academy
                               2128 S. St. Louis
                               Chicago IL  60623
                               (312)534-1680

Objective:

This lesson is designed for primary level students.  They will observe the 
transfer of momentum.

Materials Needed:

2 or more pairs of rollerblades 
2 cars - each car has a spring attached to the front bumper and velcro attached
  to the rear bumper.
a weight (that will fit on one of the cars)
cue balls
cue stick
marbles
string

Strategy:

Begin with a roller blade demonstration.  Tell the students they will need to 
observe what happens.  Students of approximately the same weight will put on 
rollerblades and will participate in four demonstrations.  (Be sure students 
wearing roller blades are also wearing helmets and other protective gear.) 

     l.  One person stands still.  The other person skates into him.  At the 
         point when they would collide, they push off from each other.

     2.  Repeat above, but this time, as they meet they grab on to each other.

     3.  Both students skate towards each other.  When they meet, they push off 
         from each other.

     4.  Repeat above, but this time, they grab on to each other.

This entire series can be repeated using one heavier student (or two students 
together) and one lighter student.  See if the results are the same.  If 
possible, let all students try these demonstrations with a partner.

Now repeat the demonstration using the 2 cars.  The students will observe and 
discuss what they see.  The teacher can draw the diagrams of the car's movement 
on the board.

     1.  One car moving - one car still.  The springs on the cars are facing 
         each other.  Observation:  The moving car stops and the still car 
         moves in the same direction the moving car was going.

     2.  One car moving - one car still.  The velcro on the cars is facing each 
         other.  Observation:  The cars stick together and move slowly in the 
         direction the moving car was going.

     3.  Both cars moving towards each other.  The springs on the cars are 
         facing each other.  Observation:  Each car moves in the opposite 
         direction but slower. 

     4.  Both cars moving towards each other.  The velcro on the cars is facing 
         each other.  Observation:  The cars stop.

These demonstrations can be repeated putting a weight on one of the cars.  Some 
of the observations will differ.  Students should observe that movement 
transfers from one car to the other.  This is called the transfer of momentum.  
They should also see that the weight of the car (or other object) affects the 
speed and direction of the movement.   

Now do a demonstration using cue balls.  Line up two cue balls.  Have a student 
hit them with a cue stick so they move in an angle.  Use a string to show where 
the ball was hit and the path each ball takes.  The students should be able to 
see a 90 degree angle.  Ask them if they see an "L".  Repeat several times. 

Now give the students a bag of different size marbles and string and let them 
try to see what kinds of angles are made when you hit two marbles together.  
Have them observe if the angle changes when the marbles are the same compared to 
when the marbles are different.  Discuss the observations with the class. 

Performance Assessment:

Students should be able to describe what "transfer" means, when discussing 
transfer of momentum.