Motion and Force

Motion An object is in motion if the object changes position relative to a reference point Essentially, everything is in motion.

Speed The distance traveled divided by the time it takes to travel the distance Speed = Distance/Time Units: m/s, km/h (most common)

Velocity Speed of an object moving in a particular direction Objects in motion can have the same speed but different velocities Example: 45 km/h NE

Acceleration The rate at which the velocity of an object changes An object is accelerating whenever it speeds up, slows down, or changes direction Units: usually m/s 2

Force A push or pull exerted on an object Unit: Newton (N) An object’s acceleration is always a result of force When two forces act on the same object in different directions, the smaller force is subtracted from the greater – the result is the NET FORCE

Net Force = ___ N to the ______ 10 N   15 N

Balanced and Unbalanced Forces: Unbalanced forces acting on an object will change an objects motion Balanced forces are equal forces that act on an object in opposite directions – no motion

Newton’s Laws of Motion First Law:  An object at rest will remain at rest or in object in motion will stay in motion unless acted on by an unbalanced force

Second Law:  The net force on an object is equal to the mass multiplied by acceleration  Force = mass x acceleration

Third Law:  If one object exerts a force on another object, the second object exerts a force of equal strength in the opposite direction on the first  For every action there is an equal and opposite reaction

Work When you exert a force on an object that causes it to move Work = force x distance Unit: Joules (J)

Energy The ability to do work When you do work on an object, you transfer some of your energy

Potential and Kinetic Potential Energy – energy that is stored  Examples are elastic and gravitational  Usually potential energy is greatest at the highest point Kinetic Energy – energy of moving objects  Usually greatest at the lowest point