Predicting Collisions

A collision happens when two objects bump into each other. When objects collide, they can change direction, speed up, or slow down. Scientists make predictions about what will happen during a collision by looking at two important things: the size of the objects and how fast they are moving.

The mass of an object is how much matter it contains. A bowling ball has more mass than a tennis ball. When a large ball hits a smaller ball, the smaller ball usually moves farther and faster. Think of kicking a soccer ball versus kicking a basketball. The soccer ball is lighter, so it travels farther when you use the same amount of force.

Speed also matters during collisions. A fast-moving object transfers more energy than a slow-moving one. If you roll a toy car slowly into another car, both cars might move just a little. But if you push the first car fast, the second car will zoom away quickly.

When two objects of equal mass collide, they often trade speeds. If a moving ball hits a resting ball of the same size, the first ball might stop while the second ball rolls away. This is like dominoes falling in a line. Making predictions before testing collisions helps scientists understand how energy moves from one object to another. Energy is the ability to make things move or change.