PASCO SE-8747 Kinesthetics Cart KINESTHESIA-1 - Manual (Page 11)

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012-05787C Kinesthetics Cart
Experiment 3: Newton’s Second Law
“The Human Slingshot”
For a qualitative illustration of Newton’s Second Law we suggest the following demonstration
requiring virtually no setup time. This demonstration is especially valuable if student insight into
Newton’s Second Law is desired in the basic form of:
“...the larger the mass - the smaller the resulting acceleration....”
A student volunteer rides on the Kinesthetics Cart. Four strands of 10 m long bungee cords
are placed around the back of the student rider. The ends of the bungee cords can either be held
in place by several student assistants or be attached to appropriate wall or floor mounting. The
cart and student rider are pulled back to a suitable location marked on the floor and released.
Then the experiment is repeated with the most massive and least massive student in the class.
➤ NOTE: For small classrooms it is recommended that several students are suitably positioned
to catch the student rider before (s)he collides with a wall or other object in the room. A bungee
cord catch mechanism is also conceivable.
Figure 3-1: A student holds on to the Kinesthetics
Cart while she is being pulled back to a fixed posi-
tion marked on the floor. The four strands of bungee
cord are simply placed around her back.
The fact that the accelerating force is not constant in this particular experiment does not
seem to create much problem with most students. However, if students object, the bungee cords
can simply be replaced by the constant tension apparatus (e.g. “bucket accelerator” in Experi-
ment 4).