Intro to Physics
Mrs. May
Imagine you’re sitting in line at a red light and you feel someone rear end you. You get out checking your car and the other driver. What you see is both the back of your car smashed and the other car. This is an example of an inelastic collision. Inelastic collisions are colliding objects that collide that stick together to become one and has the greatest loss of kinetic energy. Another type of collision is called an elastic collision. An elastic collision is when the objects don’t touch and no kinetic energy is lost. An example of an elastic collision is two toy trucks colliding with each other and no damage is being done. My model presentation consisted of two different explanatory examples of both types of collisions. My first model presentation was an example of elastic collisions. Using two pool balls and pushing them with towards each other, this showed an elastic collision. When the pool balls hit each other, this changed the direction they were coming from. No damage is done to the outside shell of the pool ball and no kinetic energy is lost. Unlike inelastic collisions, the pool balls do not stay together. This does not show complete elasticity but it is a great example because it has sound. My second model presentation was an example of inelastic collisions. In this model, we used an action figure to represent real people when giving the explanation. When the pool ball hits the “man” it is creating damage by crushing his bones and organs. The two objects do not leave each other after the collision, so they become one. Kinetic energy is lost, meaning there is sound. This is a great example of inelastic collisions. What are engineers in relation to physics? Well an engineer is a person who builds, designs, or maintains engines, machines, or public work. Many engineers develop new things. Engineering is applied physics. Physics is figuring out why things work and engineering is the practice of making things work. Engineers have created ways to prevent less damage in collisions. The damage done to a car in a collision is caused by the amount of external force by one car or the other. More damage is done if there is a great amount of force behind a collision. The damage affects the people inside of it too, causing injuries. But engineers have come up with ways to prevent less damage in a collision, affecting the passengers. For example, the bumpers on a car protect from damaging that part of the car greatly and the airbags that automatically go off in a collision protects the passengers in the car. Newton’s Second Law relates to this. It is defined as the acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. The acceleration depends on the net force upon it and the mass of the object. When an object has force acting upon it greatly, the acceleration of the object increases. But if an object has a great amount of mass, the acceleration of that object decreases. For example, an average semi truck weighs around 80,000 pounds. But for instance if they are taking off at a green light, the acceleration is not as fast as an average car. If the truck is in a collision, the breaking time is not as quick as a car, meaning crashing and creating a lot of damage to the other car. The direction of net force is the same direction as acceleration. Engineers have come up with new ways to solve elastic collisions. First you design the velocities for each object before the collision. Then choose a positive direction. Second, write the conservation of momentum principles, along with kinetic energy. Finally, solve the system of