Forces and Motion – Collisions

A collision occurs when an object hits another object. A collision can occur between two objects in motion, or by an object in motion and an object at rest. During a collision, kinetic energy is transferred between the colliding objects. A collision occurs when a tennis player hits a tennis ball. Kinetic energy is transferred from the player’s moving tennis racket to the ball, causing it to move. The more kinetic energy that is transferred, the faster and farther the tennis ball will move. During a collision, the faster an object is moving, the greater the energy transfer and the greater the impact on the other object. We can see this by looking at car accidents. If the cars are traveling slowly at the time they collide, there may be little damage to the cars. If the cars are traveling faster, there is a much more observable impact. There is likely to be more damage to the cars. The observable impact of a collision reflects how much energy was transferred between objects and relates to the amount of energy of the moving object. At the start of a game of billiards, a player uses a large force to hit one ball into the other balls. The ball gains kinetic energy from the billiard cue and moves down the table. As it hits the other balls, a loud sound is made. Kinetic energy is transferred to the other balls as they scatter all over the table. When a player uses a smaller force, less kinetic energy is transferred. The balls produce a softer sound when they collide and move more slowly. Motion is the process of changing position. When something is moving it is in motion. An object that is in motion has kinetic energy. We can describe motion by measuring its speed and direction. Speed is the time it takes an object to cover a certain distance. The faster an object covers a distance, the greater its speed. Direction is which way an object is moving. The greater the speed of an object, the more energy it has. Forces can also affect the motion and energy of an object. Larger forces will cause objects to move faster and have more energy than smaller forces. All forms of energy can be described as either stored energy or moving energy. The stored energy in an object is called potential energy. Food has potential energy. The energy is transformed into other forms when we eat the food and use the energy to move about, keep warm and stay healthy. Potential energy is also related to the shape and position of an object. If you hold a ball above your head, the ball has potential energy due to its position. If you drop the ball, the potential energy is transformed into moving energy. When potential energy is released, it is converted into kinetic energy. Kinetic energy is the energy of an object due to its movement. All moving objects, from the tiny particles that make up our air to an airplane flying in the sky, have kinetic energy. The amount of kinetic energy in an object depends on how fast it is moving. The faster an object moves, the greater its kinetic energy.

Next Generation Science