®
2 - A x i s F o r c e P l a t fo r m
Su g g e s te d A c ti v i t i e s
4
Vertical Jumping
Stand on the platform and jump vertically. Look at a graph of force versus time to
determine your “hang time,” or how much time you spend in the air. Is you hang time
related to how high you jump? What other factor affect hang time? (For more precise
time measurements, use a higher sampling rate.) Do you apply any horizontal force to
the platform when jumping (and landing) vertically?
Leaning
Place the platform on the floor near a wall. Stand on the platform while observing
horizontal and vertical force. Lean against the wall with slowly increasing force. How
do the measured vertical and horizontal forces change?
Horizontal Jumping
Jump forward off of the platform. Turn around (while standing in the same spot where
you landed) and jump back onto the platform. Compare the horizontal and vertical
forces of jumping off and jumping back on.
Vertical Impulse
Use a motion sensor (PS-2103) to measure the position and
velocity of the top your head as you jump vertically on the
platform. What is your measured vertical velocity at the
moment your feet leave the platform? If you assume that you
are a point mass, does this velocity correspond with your mea-
sured hang time? Why not?
Stand on the platform and press the tare button. Bend your
knees and jump with one smooth motion. The area under the
force versus time plot is the impulse. How does the impulse of
jumping compare to the impulse of landing? Using the mea-
sured impulse, calculate your launch velocity.
Compare the velocity measured by a motion sensor to the
velocity calculated from the impulse. Why are they not neces-
sarily equal?
Horizontal Impulse
Hang the platform on a wall. Press the tare button. Sit on a rolling chair, a kinesthetics
cart (SE-8747), or a hovercraft (ME-9838) and push off against the platform. Measure
the impulse, or the area under a plot of force versus time. How is the impulse related
to your momentum immediately after pushing off?
Use a motion sensor (PS- 2103) to measure your velocity as you push off. Use this
velocity to calculate your momentum and compare it to the impulse. (Remember to
take into account the mass of the person
and
the chair, cart, or hovercraft.)
Force Distribution (With a Single Platform)
On a graph, display the separate force measurements of each of the platform's four
beams. Stand on the platform and slowly shift your weight from your left foot to your
right foot. Slowly shift your weight from your heels to your toes. What happens to the
forces measured at the four corners of the platform? What happens to the sum of these
forces?
Motion Sensor
