Motion And Forces SC & SC May the force be with you!

Mass vs. Weight Mass is the amount of “stuff” in an object, or the measure of inertia of an object. Mass is the amount of “stuff” in an object, or the measure of inertia of an object. Weight is the pull of gravity on an object. Weight is the pull of gravity on an object. –An object’s mass is the same throughout the Universe, but your weight changes depending on what planet your on. –Because the gravitational pull on Mars is less than Earth, you weigh less on Mars, but your mass is the same at both locations.

Motion Motion is the change in position of an object, measured by distance and time. Motion is the change in position of an object, measured by distance and time.

Force A force is any push or pull on an object. A force is any push or pull on an object. –Forces give energy to objects. –Forces cause a change in the motion of an object.

Frame of reference The point from which movement is determined. The point from which movement is determined. –To measure movement, some point must be considered as nonmoving. –Earth is the most common frame of reference.

Speed The distance traveled by a moving object per unit of time. The distance traveled by a moving object per unit of time. –To calculate speed, use the equation: Speed = distance/time - Speed only gives distance and time.

Average Speed The speed of a moving object is not always constant The speed of a moving object is not always constant Average speed = total distance/total time Average speed = total distance/total time

Velocity Velocity is the speed of an object in a given direction. Velocity is the speed of an object in a given direction. –Velocity gives distance, time and the direction of travel.

Acceleration Is the change of speed over time. Is the change of speed over time. Deceleration occurs when the change in speed, or acceleration, is in the negative direction. Deceleration occurs when the change in speed, or acceleration, is in the negative direction. –Commonly used to mean a decrease in speed.

Sir Isaac Newton An English mathematician and physicist who discovered one of the most important relationships in physics: the relationship between the force on an object, its mass, and its acceleration. An English mathematician and physicist who discovered one of the most important relationships in physics: the relationship between the force on an object, its mass, and its acceleration.

Newton’s First Law of Motion An object will stay at rest, while an object in motion will stay in motion, unless acted upon by an unbalanced force. An object will stay at rest, while an object in motion will stay in motion, unless acted upon by an unbalanced force. * In other words, unless you apply a force to an object, it tends to keep doing what it was doing in the first place.

Inertia Newton was the first to use the term inertia to describe the tendency of object to remain in motion or stay at rest. Inertia comes from the Latin word iners, which means lazy. Newton was the first to use the term inertia to describe the tendency of object to remain in motion or stay at rest. Inertia comes from the Latin word iners, which means lazy.

Newton’s Second Law of Motion The acceleration of an object is directly related to the force acting on it and inversely related to the object’s mass. The acceleration of an object is directly related to the force acting on it and inversely related to the object’s mass.  Force = mass x acceleration –In other words, force causes an object to accelerate, while the object’s mass resists acceleration.

Newton’s Third Law of Motion For every action, there is an equal but opposite reaction. For every action, there is an equal but opposite reaction. In other words, all forces act in pairs In other words, all forces act in pairs

Friction Friction is a force that opposes motion. Friction is a force that opposes motion. –Friction always works against the motion that produces them. –There are 3 types of friction:  Fluid Friction  Sliding Friction  Rolling Friction