# Kicking off the 2012 Summer Olympics with Soccer & Physics

Tonight kicks off the 2012 Summer Olympic Games in London! With over 10,000 athletes competing from 204 different countries, there will be lots of tough competition to bring home a gold medal. A combination of skill, dedication, and physics will be necessary for the U.S. Women’s soccer team to stay in the competition. Yep, physics. To find out more about how the laws of physics are at play in the game of soccer we caught up with one of our Senior Science Mentors, Kristin M., who explained just that. Learn all about it below!

When most people think of soccer, they think about goals being scored or fantastic saves being made by defenders or goalies. As a former high school physics teacher, I see the laws of physics at play throughout the field.  From long kicks by defender/right back Heather Mitts, to headers by forward Abby Wambach, to fabulous saves by goalkeeper Hope Solo, my love for the game of soccer is compounded as I watch Newton’s Laws play out on the field. But it’s likely rare that the average person watching the game sees just what I am seeing.  So let’s take a look at some of the things at play.

We can start by considering Newton’s first law: inertia.  This law tells us that an object will keep moving in a straight line unless acted upon by an outside force.  We see this law all over the playing field, from goalkeepers especially. Once a shot is taken on goal, the ball wants to continue on its path straight towards the goal.  Hope Solo knows that her job is to redirect the ball. Since Olympic athletes often have quite strong shots, it is often difficult to catch the ball. But simply touching the ball, as you often see Hope do, is enough to utilize the speed the ball has and an outside force, her hand, to get the ball over the cross bar or just around the outside of the post. The same can be said for offensive players waiting in the box to score from a header or other redirection during a corner or free kick. Abby Wambach can simply apply an outside force to the ball, using its initial speed, to direct the ball past the goalkeeper. Because the ball is moving swiftly, Abby often only needs to get a body part on the ball in order to score.

The other reason such a small force is needed is related to Newton’s second law and the size of the ball.  Soccer balls have a very small mass, so a small force will create a great acceleration. Light materials are generally chosen in the production of elite level balls so that the mass of the ball doesn’t become a hindrance to the game and instead we are able to watch the skill of the players. Newton’s second law is often used to derive the concept of impulse as well, something we see repeatedly throughout the game as players touch the ball. On free kicks, a player’s foot is in contact with the ball for a longer length of time, allowing them to give the ball a larger final speed than the same force applied over a shorter time.

So when you get a chance to watch the soccer matches during the upcoming Olympics, take some time to see what physics laws you see at play. Small touches by Hope Solo, Abby Wambach, and Heather Mitts will likely be the difference in goals being scored or saved due to the high velocity the ball often travels at.