Energy + Motion

Key Terms

• Inertia - The tendency of an object to resist change in its motion

• Net Force - The force caused by the combination of multiple forces acting on a single object; also called resultant force

• Mass - The amount of matter in a substance or object, measured in grams (g), kilograms (kg), or tonnes (t)

• Action-reaction Force Pair - A pair of forces acting between two objects; the forces are of equal magnitude and opposite direction

• Magnitude - A measure of the size or strength of something

• Scalar - A quantity that consists of a measurement of magnitude only

• Vector - A quantity that has magnitude and direction

• Force - Any interaction that will change the motion of an object when unopposed; for example, a push or pull

• Distance - A measurement of the length of a path between two points; unlike displacement, distance does not have to be a straight line

• Displacement - A measurement of the change in position of an object; a straight line connecting the start and end points is specified in terms of length and direction

• Speed - The rate of change of distance

• Instantaneous Speed - The speed of an object at a particular moment

• Average Speed - A measurement of how fast something moves over a given time interval

• Velocity - How fast an object is moving, as well as the direction it is moving in

Newton’s Laws of Motion

Newton’s First Law:

• An object remains at rest or remains in motion at a constant speed and direction unless acted upon by a net external force