Physical Science Laws of Motion

Objectives Identify the law that says that objects change their motion only when a net force is applied Relate the first law of motion to important applications, such as seat belt safety issues Calculate force, mass, and acceleration by using Newton’s second law

Inertia- the tendency of an object to resist being moved or, if the object is moving, to resist a change in speed or direction until an outside force acts on the object –Ex) Newton’s cradle

Newton’s First Law : –An object at rest remains at rest and an object in motion maintains its velocity unless it experiences an unbalanced force –Ex) traveling in car, it stops, your body goes forward. Seat belts are designed to counteract this effect

Inertia is related to an objects mass Newton’s first law = law of inertia Mass is a measure of inertia An object with a small mass has less inertia than a larger mass object It is easier to change the motion of an object with a small mass –Ex) golf ball vs. bowling ball

Newton’s Second Law States: –The unbalanced force acting on an object equals the object’s mass times its acceleration Force = mass x acceleration F=ma * Newton’s Second Law describes the effect of an unbalanced force on the motion of an object (a force is applied)

Newtons Write on index card Force is measured in newtons (SI unit) 1N= 1kg x 1m/s2 1N= lb 1lb= N F=mam=F/aa=F/m

Read Complete practice problems 1-3 Math skills 4-6