To measure horizontal displacement you would need to measure horizontally from the center of gravity at take-off to the center of gravity at landing. However, you may have noticed that since we are viewing the skater on a computer monitor, he is much smaller than in real life. Thus, the displacement you measure is not the actual real life distance of the jump, but a scaled down version of the actual distance. To convert this number to the actual real life distances you need a scale factor. Measure the distance from the skaters right hip to knee at take-off. This distance in real life is 43 cm. Divide this real life distance by your measured distance. For example, on our computer monitor the distance from the hip to knee is 1.5 cm. Thus you can make a ratio:
real life distance/ measured distance = 43 cm/1.27cm = 34
This number tells you that the view of the skater on the monitor is 34 times smaller than he is in real life. To calculate your own scale factor click here to see a picture of the skater at take-off.
Now you are ready to measure the jump distance. Any ruler will do.
To convert this jump length measurement to a real life horizontal displacement, you need to multiply by your scale factor:
real distance = measured distance x scale factor
For example, on our monitor we got:
measured distance = 15.24
scale factor = 34
real distance = 15.24 cm x 34 = 518 cm = 5.18 m
Your answer should be close to 5.18 -- it's hard to measure accurately on the screen! But, if it's way off, try again.
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