# Science 3q test

 What is acceleration? The rate at which velocity changes. Acceleration happens when: a. Speed increases (thus acceleration increases) b. Speed decreases (called negative acceleration) c. Direction changes ( ex. Seats on a ferris wheel are constantly accelerating because the are constantly changing direction.) What is the acceleration formula for an object traveling in a strait line? final speed - initial speed / time Force definition A push or pull. Like acceleration, force is described by it's strength and by the direction in which it acts. Strength Strength is measured in newtons (N) Direction (of force) Represented by an arrow pointing in the direction of the force. The longer the arrow, the greater the force. Combined (or net) forces All the forces acting on an object Balanced forces (definition) Equal forces acting on one object in opposite directions. Balanced forces do not change the object's motion. Unbalanced Forces When they act on an object they result in a net force and cause a change in the object's motion. Friction (definition) A force that resists motion. Produced by surfaces or materials rubbing together. Static friction acts on objects that are not moving sliding friction happens when two solid surfaces slide over eachother Rolling Friction Happens when an object rolls across a surface. Fluid friction Happens when a solid object moves through a fluid Gravity (definition) A force that pulls objects toward each other. It depends on mass and distance. The greater the distance, the weaker the force. The greater the mass, the greater the force. Weight changes based on the gravitational force of the planet. Mass does not. AuthorAnonymous ID76406 Card SetScience 3q test DescriptionThese are the study cards for the third quarter science test. Updated2011-03-31T11:12:36Z Show Answers