LAB # 2: Forces & Torques KIN 2241B Biomechanics Winter 2013

DUE:
give completed LAB assignment to either Peter Wegscheider or Ashley Hannon in any 2241B class prior to but no later than the class on Monday 11-Feb-2013. This is the only method of submitting your completed lab assignment. Late submission will not be accepted and a zero will be assigned.

FORMAT: Lab assignment must be typed on a standard sheet of paper (8.5" x 11") using type font size of 10. The report must not exceed two pages and if you require two pages to complete the assignment, it must be printed double-sided on one page (use a duplex mode printer or photocopier to get a one-page report). Note: a mark penalty will be assessed for any report submitted on more than one sheet of paper.

ASSIGNMENT: see text Chapter 12 pages 392-395 and FIG 1.2 on page 328 for some assistance

1. Examine the skill of High Jumping using the “Backward Layout” technique aka “Flop”. The below video link might be of assistance, but you can use any resources you wish.
"High Jump Closer look at the high jump approach” http://www.youtube.com/watch?NR=1&feature=endscreen&v=__B7aTvFJ7U

Note: you might find it helpful use pause control when you need to go slow motion frame by frame

2. Answer the below questions:

2-1 If we divide the high jumping into two phases – one while the jumper is on the ground (approach & takeoff) and the other when the jumper is airborne, in which phase are torques internal and in which phase are torques external?

2-2 During takeoff while the jumper is still in contact with the ground, what effect does the movement upward of the leading leg and the arms have on the jumper’s body?

2-3 During final phase of the approach run to the bar and up to and including the final takeoff position, what causes the jumper’s body to move from a position leaning away from the pit to a position leaning slightly towards the pit?

2-4 Use Figure 12.5 b on page 394 of the course textbook as a reference and draw a “Stick Figure” diagram that represents that position of the jumper at that instant of takeoff from takeoff foot up to head.

Next, draw and label the following:

ü a mark (e.g. X) to represent the location of the jumper’s Center of Gravity (CofG)

ü vectors that reasonably represent the horizontal and vertical reaction forces that comprise the resultant direction of force propelling the jumper upward as well as toward and over the crossbar

ü the resultant force vector (angle of body projection)

ü the Force Arm (FA) of the net Torque (T) that will cause the body when airborne to rotate backward towards the pit