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  1. Physics of Swimming When i first looked up the physics of swimming, i got many different answers. There were many different ways that swimming can tie into physics. I am going to give a formula that is on the refrence table and can relate to because weve used it in physics class before. To kick 100 meters it takes 80 seconds. When kicking, a swimmer can travel at a velocity of 1.25 m/s. To pull 100 meters it takes 60 seconds. When pulling, a swimmer can travel at a velocity of 1.6 m/s. To swim 100 meters with both the arms and the legs it would take 50 seconds. When swimming using both the arms and the legs, a swimmer has a velocity of 2 m/s. The arms therefore generate more propulsion than the legs. The propulsion generated by the legs is 62%. The propulsion generated by the arms is 83%. The ratio of pull to kick is 1.3, meaning that the pull is 1.3 times greater than the kick. Water applies a force perpendicular to each surface of the swimmer's body. F = PA The force acting perpendicular to the surface of the swimmer's body is equal to the pressure acting on the swimmer mulitiplied by the surface area. For example, if the Pressure acting on the back of a swimmer's hand 1.3 x 10^5 Pa and the surface area of the back of the hand is 8.3 x 10^-3 m^2 then the equation F = PA would yield: F = (1.3 x 10^5 Pa) * (8.3 x 10^-3 m^2) = 1079 N. As you can see alot of the information would just be plugging in the informations thats given to you. You can also see that it takes alot of work to swim, its also been said that swimming is the best workout you could do for your body. I hope i have opened your eyes to a new way of thinking about swiming, especially with sumer coming up, thank you for reading my blog
  2. There is a lot of physics though out the process of roller blading. There is Newtons 1st law, friction, work, and if your not too good at it; collision. Newtons 1st Law: Also known as the Law of Motion, Newton's 1st law states that if the net force exerted on an object is zero, the object continues in its original state of motion. In other words, if your rolling down a hill with no breaks, your wont stop until something gets in the way to stop you. Friction: Kinetic friction is the frictional force for an object in motion. The magnitude of the force of kinetic friction acting between two surfaces is given by the equation. This is best used when trying to stop, you would put the toe stopper to the floor so the friction between the ground and skate would cause you to slow down or stop completely. Work: Work is defined as the product of the component of the force along the direction of displacement and the magnitude of displacement. This comes into play if your just learning how to skate, the person teaching you may have to hold you up, therefor doing work. Collision: In an elastic collision, momentum and kinetic energy are conserved. This is for when you just begin skating or aren't very good, you tend to fall or run into things which causes a collision. I hope you enjoyed my blog entry on the physics of roller blading, and I hope this helped you see all the ways that physics connects to roller blading.
  3. Physics of Hockey — The Slapshot In the slapshot, players can clock puck speeds of over 100 miles per hour, making it the hardest shot in hockey. The hockey player begins the slap shot by raising the stick behind his body, as shown below. http://en.wikipedia.org/wiki/Slapshot Next, the player violently strikes the ice slightly behind the puck, and uses his weight to bend the stick, storing energy in it like a spring. When the face of the blade strikes the puck the player rotates his wrists and shifts his weight in order to release this stored energy and transfer it to the puck. The result is the puck reaching a speed faster than it would if the player simply hit the puck directly. The kinetic energy of the puck after impact is equal to the stored energy in the hockey stick. The figure below shows the point of impact between the stick and puck. You can clearly see the bend in the stick. 130308183657-zdeno-chara-2-single-image-cut.jpg The physics of hockey taking place here is the transfer of energy from player to stick, and from stick to puck. The advantage of storing energy in the stick is that (upon release) it strikes the puck faster than the player can, causing the puck to reach a greater speed. The player applies a force to the hockey stick. The friction between the stick and ice forces the stick to bend and create potential energy. The player transfers weight from their back leg to their front leg to put more force on the flex of the stick. The blade of the stick is up in the air at the end of the shot to push the puck up against gravity. When the potential energy is released, the stick snaps back and transfers its energy to the puck. The stiffer the flex the more potential energy, when flexed, The puck shot in the air will have a curved path coming back to the ice due to gravity. The puck accelerates in the direction that the sticks force is applied on it (Newton’s 2nd Law) the player puts all their weight on their back leg and raises their stick above their head creating potential energy. The type of stick used has a big impact on how hard a shot will come off. Composite sticks will have a better flex which means more potential energy with having a less chance of the stick snapping. Acceleration of the puck is determined by how much force is applied to the stick.
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