I wanted to know how many Newtons of force I use to kick a football. I wrapped the ball in foil and weighed it. It has a mass of 0.385kg.
I needed to time the contact between my foot and the ball. I used the Scaler/Timer on "timing" mode with the leads conected to Start and Earth. In this mode, it times how long the two leads are in contact when they touch.
The contact time recorded was 0.039 seconds.
Stopping the film showed that the ball had gone 3.25 metres. The table was 0.85 metres high. Using the suvat equation s=ut+1/2at^2 for the vertical drop of the ball, it was in the air for 0.41 seconds. Assuming constant horizontal speed, the ball left my foot with a speed of 3.25/0.41=7.8m/s. So after the kick, the ball had a momentum of 0.385 x 7.8 = 3.0kgm/s. It had 0 momentum before the kick so the change in momentum was 3.0kgm/s. The kick lasted 0.039 seconds so using force = change in momentum/time taken, F=3.0/0.39 = 77N.
Next I put foil on my shoe to kick the ball.
I then filmed how far along the ball went.
