Speed, Velocity, Acceleration, Speed, Velocity, Acceleration, & Force& Force

Motion: The change in Motion: The change in positionposition of an object of an object

ReferenceReference Point: a place or object used for Point: a place or object used for comparison to determine if something is in motion. comparison to determine if something is in motion. (also called frame of reference)(also called frame of reference)

An object is in motion if it changes An object is in motion if it changes

position relative to a reference point.position relative to a reference point.

Forces put things in motion Forces put things in motion

(starts at 1:11)(starts at 1:11)

We're All in Motion video clip

(starts at 16 min.)

Speed: The Speed: The distancedistance an object travels in one unit of time. an object travels in one unit of time.Average Speed (average velocity): v = d ÷ t Average Speed (average velocity): v = d ÷ t (v = velocity, d = distance, t = time)(v = velocity, d = distance, t = time)Example: an object rolls 2 meters in 4 seconds. Example: an object rolls 2 meters in 4 seconds. 2 ÷ 4 = 0.5 m/s2 ÷ 4 = 0.5 m/sTo solve for missing factor To solve for missing factor when the other 2 are known: when the other 2 are known: t = d ÷ v or d = v∙tt = d ÷ v or d = v∙t

VelocityVelocity: Speed in a given direction: Speed in a given direction

(example: 10 km/hr north)(example: 10 km/hr north)

GraphGraph: a picture of the data used to : a picture of the data used to assist in data analysisassist in data analysis

Acceleration: The rate at which Acceleration: The rate at which velocityvelocity changes {change in speed changes {change in speed and/or direction} and/or direction} Acceleration: a = vAcceleration: a = vf – vif – vi

tt(a = acceleration, vf = final velocity, vi = initial velocity, t = (a = acceleration, vf = final velocity, vi = initial velocity, t =

time)time)

Ex: an objects initial velocity is 2 m/s but increases to 4 m/s Ex: an objects initial velocity is 2 m/s but increases to 4 m/s second after 5 secondssecond after 5 seconds

4 m/s – 2m/s4 m/s – 2m/s = = 2 m/s2 m/s 5 s 5 s5 s 5 s 0.4 m/s 0.4 m/s22

Δ (delta) is a symbol that means change in. Δ (delta) is a symbol that means change in.

To solve for missing factors when the other 2 are To solve for missing factors when the other 2 are known:known: a = Δv÷t a = Δv÷t

Δv =a∙t Δv =a∙t

t = a∙ Δvt = a∙ Δv

Force: A Force: A pushpush or or pullpull exerted on an object exerted on an objectNewtonNewton (N): A unit of measure for force. (N): A unit of measure for force.

1 N = the force required to accelerate 1 kg of mass at 1 m/s1 N = the force required to accelerate 1 kg of mass at 1 m/s22

BalancedBalanced Forces: Equal forces acting on an object in Forces: Equal forces acting on an object in opposite directions (no change in motion)opposite directions (no change in motion)UnbalancedUnbalanced Forces: Forces: A nonzero net force, which A nonzero net force, which changes an object’s motion.changes an object’s motion.NetNet Force: The overall force Force: The overall force on an object when all individual on an object when all individual forces acting on an object are forces acting on an object are added together.added together.

The 4 Fundamental Forces:The 4 Fundamental Forces: 1.1. GravityGravity: The force that pulls objects : The force that pulls objects

toward each other toward each other (more (more detail in later units)detail in later units)

2. 2. NuclearNuclear Forces Forces Strong Force: force in the nucleus Strong Force: force in the nucleus

that causes protons and neutrons that causes protons and neutrons to be attracted to each other. to be attracted to each other.

Weak Force (electrical force) is a Weak Force (electrical force) is a long range force and causes long range force and causes repulsion of protons far apart. repulsion of protons far apart. It is responsible for the decay of It is responsible for the decay of

isotopes isotopes (more in chemistry).(more in chemistry). 3.3. ElectromagneticElectromagnetic force force (more detail in later units)(more detail in later units)

4. 4. DarkDark Energy : believed to be the Energy : believed to be the cause of universal expansion cause of universal expansion (space science)(space science)

4 forces video clip