help physics question

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SpiritoftheTunA

United States20903 Posts

February 22 2008 04:43 GMT

#21

On February 22 2008 12:30 Chill wrote:

Show nested quote +

Thanks for your help and suggestions to help the OP!

yeah no problem, same to you by the way

well i mean, OP didn't mention what he's able to measure. time of impact, instant accel (easily), get a graph of position vs time up, or what. it's pretty impossible to make a suggestion from what he gave me. so hey, kdog... whatcha got?

edit: to improve on chill's pendulum idea though, ok... (just to make everything easier to measure)

tie a ball to a string, hang it vertically, make sure it's stationary
kick it lightly
measure the angle it deviates from the vertical (with a protractor facing down, oriented around the pivot point)
also measure the time it took to get to that angle

~~Uinitial~~ (potential energy - set your zero point here so it's zero) + Kinitial = Ufinal + ~~Kfinal~~

1/2mvsquared = mgh where h = L (length of pendulum) - Lcostheta where theta is angle from vertical

find out v (which will be initial velocity)

find out time of impact

divide for accel

multiply by mass for force

or something

skyglow1

New Zealand3962 Posts

February 22 2008 07:05 GMT

#22

I thought of finding out the average force because I felt measuring velocity of the ball just after it leaves the foot is much easier than finding the instantaneous acceleration at that point.

The idea of using a video cam would work really well with this I think if you could have a high enough frame rate. You could put some sort of a scale behind the ball which has really clear divisions at every 1 cm or somethinng to measure the velocity of the ball just after it leaves the foot, and you could measure how long in contact the foot is with the ball, adn measure the mass of the ball.

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