Finding the Ball Velocity

    The easiest way to calculate the Ball velocity is to take the length of the lane and divide that by the time it took to travel the length of the lane.  This of course is just a really long way of saying that v (velocity)= d (distance)/t (time).  For your knowledge the length of the bowling lane is 60 feet (18.3 meters).  If it took the ball took, say, 4 seconds to reach the end of the lane then the velocity of the ball is 15 feet per second (4.575 meters/second).  All of this becomes fodder when you start to include the friction between the ball and the lane.  In reality the ball has a higher velocity when being released and a lower one when nearing the end of the lane.

Finding the Ball Spin

   Calculating the ball spin is another matter all together.  There are only two real methods to do this.

1. Put a piece of tape above the finger holes.  Roll the ball with your normal stride.  Have a friend count the number of times that the piece of tape rotates until the ball hits the pins. Note: this is not an accurate way of doing this.

2. If you have a digital camcorder the process if much easier.  You still Follow method One but instead of a friend, you use the camcorder to record your roll.  You then replay the footage frame by frame to get a most accurate figure.

The Hook Dilemma

   Have you ever noticed how one ball hooks more then another one.  This is caused by one ball having a greater radius of gyration (Rg).  Rg is a way of telling how the mass and density of a ball is distributed.   The way that Rg is useful is when planning how the ball will spin.  You can compare bowling balls with known masses and Rg ratings with a hollow sphere of equal mass and a radius equal to the Rg in inches.  For example, a 12 lb ball with a Rg of 3 will act the same as a 12 lb hollow sphere with a 3" radius.  Rg is another measure of how close the mass is centered versus the axis on which the ball is rotating.  Now how does this apply to bowling.

   The Radius of Gyration is what cause a ball to hook and flare.  A ball with a higher Rg will travel in a straight path for a longer period of time before it hooks.  The only other known application of this in sports is in figure skating.  When the skater is performing a spin, she moves her arms in and out depending on how fast she wishes to travel.  This is because the skaters mass is closer to the axis on which her body is rotating.

Is the ball slowing down?

    During the balls path down the lane, it is highly likely that the ball will slow down towards the end.  The main cause of this is Friction.  The magnitude of the frictional force will vary depending on what type of oil is used on the lane, and the mass of the ball.   The equation to find the kinetic friction is :    µ_k=F_k/mg .  µ_k stands for the coefficient of kinetic friction and F_k stands for the Force due to kinetic friction.  m is the mass of the ball and g stands for gravity.  Now let's find µ_k for my usual shots using a 12 lb (5.45 kg) ball.  

µ_k=4.53/(5.45)(9.8)=.08319559

But why are the pins still standing...

   This little bit of physics may take a little bit more time to explain but if you understood the radius of gyration then this should be a snap.  The only reasons that the pins are still standing is because you are too weak.  no, I'm just kidding.  The true reason why is because the ball you are using has a Rg that is much too high.   When a ball has a high Rg, the coefficient of restitution is much too low.  Think of it this way.  If you took the bowling ball used in the Rg explination above and a 12 lb beach ball, which ball will cause the most pins to fall over.  Now this may surprise you but the bowling ball will.  This is because the bowling ball has a lower Rg then that of the beach ball.  When trying to do equations to discover hw strong the ball will hit the pins, simply find the inverse of the Rg.