How does a lubricant reduce friction?
Forces give energy to objects. Forces cause a change in motion. Friction: a force that opposes motion. Types of friction: • Sliding friction – when two solid surfaces slide over each other. • Rolling friction – when an object rolls over a surface. • Fluid friction – when an object moves through a fluid. Experiment withfriction. video clip Satellite Operator Aristotle and Newton had different ideas about forces and motion. Aristotle’s idea: For an object to move at a constant speed, a constant force must be applied. Newton’s idea: An object moving at a constant speed will continue at that speed without additional force being applied. • Friction is not always bad. Discuss this with your table. Think of two examples of when friction is good. Tell your science facilitator when you have them. • Ask your teacher for a ball. Go into the hall and roll (do not throw) the ball down the hall. • Carefully observe the actions of the ball. • Do your observations support Aristotle or Newton? Be able
