Chapter 2 Motion

Think About It! How would you describe speed? How would you describe speed? What would you need to know to figure out speed? What would you need to know to figure out speed? Do you need to see something move to know that motion has occurred? Do you need to see something move to know that motion has occurred?

Motion and Position A _____________________ is needed to determine position A _____________________ is needed to determine position ____________ occurs when an object changes position relative to a reference point ____________ occurs when an object changes position relative to a reference point You are moving in your chair You are moving in your chair Relative to the other ____________! Relative to the other ____________! Earth travels 942 billion meters/ year. How fast is it traveling in mi/hr? Earth travels 942 billion meters/ year. How fast is it traveling in mi/hr?

Distance and Displacement ________________: how far an object has moved ________________: how far an object has moved km, m, cm, etc. km, m, cm, etc. ________________: distance AND direction of object from starting point ________________: distance AND direction of object from starting point

Distance and Displacement

Speed _____________: distance traveled in a certain amount of time _____________: distance traveled in a certain amount of time

Constant vs. Changing Speed If speed is _______________– can calculate speed over any distance – it’ll be the same! If speed is _______________– can calculate speed over any distance – it’ll be the same! Usually speed is changing Usually speed is changing

Average Speed Calculate ___________________ by total time Calculate ___________________ by total time

Instantaneous Speed Def: speed at a given ___________ in time. Def: speed at a given ___________ in time. Speedometers show inst. speed Speedometers show inst. speed _____________ speed = inst. speed does not change _____________ speed = inst. speed does not change

Practice Problems Runner travels 200m dash in 22 s. What is the average speed? Runner travels 200m dash in 22 s. What is the average speed? You had an average speed of 70 mi/hr from the St. Leon exit to the Harrison exit on I-74. It took you 10 minutes to get there. How many miles did you travel? You had an average speed of 70 mi/hr from the St. Leon exit to the Harrison exit on I-74. It took you 10 minutes to get there. How many miles did you travel? You traveled 75 miles at 70 mi/hr from here to Indianapolis. How long did it take you in minutes? You traveled 75 miles at 70 mi/hr from here to Indianapolis. How long did it take you in minutes?

Velocity Def: speed of object AND _____________ Def: speed of object AND _____________ speed : velocity as distance : ____________ speed : velocity as distance : ____________ ________________ can change even if speed is constant ________________ can change even if speed is constant

Moving Continents

Graphing Time on ____-AXIS Time on ____-AXIS Distance on ___-AXIS Distance on ___-AXIS Constant speed = straight line Constant speed = straight line

Graphing Slope = change in y = _____ = distance = speed Slope = change in y = _____ = distance = speed change in x time change in x time Horizontal line = object at __________ Horizontal line = object at __________

Acceleration Section 2

Acceleration Def: rate of change of _____________ Def: rate of change of _____________ Could be change in speed, ____________ or both Could be change in speed, ____________ or both Speeding up  ______ acceleration Speeding up  ______ acceleration Slowing down  ______ acceleration Slowing down  ______ acceleration Speed is changing = acceleration Speed is changing = acceleration

Acceleration + acc. = going in _________ direction as velocity + acc. = going in _________ direction as velocity -- acc. = going in _______________ direction as velocity -- acc. = going in _______________ direction as velocity

Acceleration Changing _______________ is changing velocity and acceleration Changing _______________ is changing velocity and acceleration Speed is constant Speed is constant

Calculations If ___________ doesn’t change velocity = speed If ___________ doesn’t change velocity = speed Units: m/s 2 Units: m/s 2

Positive Acceleration Jet airliner starts at rest and reaches a speed of 80m/s in 20s. Calculate the acceleration. Jet airliner starts at rest and reaches a speed of 80m/s in 20s. Calculate the acceleration. Has positive slope on graph Has positive slope on graph

Negative Acceleration Skateboarder comes to rest in 2s after a speed of 3 m/s. What is his acceleration? Skateboarder comes to rest in 2s after a speed of 3 m/s. What is his acceleration? Has negative slope on graph Has negative slope on graph

Time Calculations A car had a negative acceleration of 4 m/s 2 when it stopped after having a rate of 40 m/s. How long did it take for the car to stop? A car had a negative acceleration of 4 m/s 2 when it stopped after having a rate of 40 m/s. How long did it take for the car to stop?

Final Velocity Calculations If a vehicle has an initial velocity of 35 m/s accelerates at 20 m/s 2 for 5 seconds, what is it’s final velocity? If a vehicle has an initial velocity of 35 m/s accelerates at 20 m/s 2 for 5 seconds, what is it’s final velocity?

Motion and Forces Section 3

What is force? Def: a ___________ or ___________ Def: a ___________ or ___________ Kicking a ball, throwing a ball, etc. Kicking a ball, throwing a ball, etc. ____________has a force on you, atmosphere’s force, etc. ____________has a force on you, atmosphere’s force, etc.

Changing Motion Force causes motion to _____________ Force causes motion to _____________

Balanced Forces __________________: combination of two or more forces act on an object at same time. __________________: combination of two or more forces act on an object at same time. _______________ Forces: forces equal in size but in opposite direction _______________ Forces: forces equal in size but in opposite direction Net force = 0 Net force = 0

Unbalanced Forces ______________________________ forces - net force will be the difference between the two and move in direction of bigger force ______________________________ forces - net force will be the difference between the two and move in direction of bigger force

Same Direction Forces Net force is ________ of the two and moves in that ____________ Net force is ________ of the two and moves in that ____________

Inertia and Mass _______________: tendency to resist any change in motion _______________: tendency to resist any change in motion Stop a bowling ball vs. ping pong ball Stop a bowling ball vs. ping pong ball _________________ of object  greater inertia _________________ of object  greater inertia Newton’s _______ Law of Motion Newton’s _______ Law of Motion

Newton’s 1 st Law of Motion Sir Isaac Newton ( ) Sir Isaac Newton ( ) Def: Object moving at constant ______________ keeps moving at that velocity unless an ________________ net for acts Def: Object moving at constant ______________ keeps moving at that velocity unless an ________________ net for acts Sometimes called “Law of Inertia” Sometimes called “Law of Inertia”

Car Collisons Seat belt vs. No seat belt Seat belt vs. No seat belt Speed of _______ km/hr collides with wall Speed of _______ km/hr collides with wall Car stops in _____ Car stops in _____ No belt = person keeps moving at _________km/hr No belt = person keeps moving at _________km/hr Seat belt = slows person to stop (air bags help too) Seat belt = slows person to stop (air bags help too)