Kinematics – deals with concepts describing motionKinematics – deals with concepts describing motion

Dynamics – deals with the effects that Dynamics – deals with the effects that forcesforces have on motion have on motion

Mechanics – Kinematics and Dynamics make up the branch of physics Mechanics – Kinematics and Dynamics make up the branch of physics called Mechanicscalled Mechanics

Displacement: It is a vector showing the initial position and final position of an Displacement: It is a vector showing the initial position and final position of an object. (object. (SI unit:SI unit: meter) meter)

Speed = distance time

Velocity is speed + directionA plane flies at 100 mph from MinneapolisTo Chicago (a distance of 325 miles). How Long will the flight take to get there?

A) 3250 minutesB) .31 hours C) 3 hours and 15 minutesD) 3 hours and 25 minutesE) 2 hours and 45 minutes

Kinematics One DimensionKinematics One Dimension

Average Velocity = displacement / elapse time or Average Velocity = displacement / elapse time or total distance / total timetotal distance / total time

Instantaneous Velocity = Your speed and direction at any Instantaneous Velocity = Your speed and direction at any given moment in time.given moment in time.

The space shuttle travels at 7,600 m/s. You start and stop a The space shuttle travels at 7,600 m/s. You start and stop a stopwatch as quickly as you can and get .05 sec. About stopwatch as quickly as you can and get .05 sec. About how many football fields (96m) can the space shuttle travel how many football fields (96m) can the space shuttle travel in the time it takes you to start and stop a stopwatch?in the time it takes you to start and stop a stopwatch?

A) 1A) 1 B)2B)2 C) 3C) 3 D) 4D) 4 E) 5E) 5 F) 8F) 8 G) 11G) 11 H) 14 H) 14

If you can “feel it” it’s accelerationIf you can “feel it” it’s acceleration It is the It is the rate of change rate of change in velocityin velocity Speeding up, slowing down, changing Speeding up, slowing down, changing

directiondirectionAcceleration = Vfinal – Vinitial

time

If a baseball goes from 0 – 50 m/s In half a second. What is the accelerationOf the baseball?A)100 m/s2

B)0 m/sC)200 m/s2

D)100 m/sE)125.5 m/s2

It is how much is your speed changing each second

meters / seconds / secondm/s2

A car on the highway is going 50 miles/hr and A car on the highway is going 50 miles/hr and passes another car and reaches a top speed of passes another car and reaches a top speed of 75 mi/hr 5 seconds after beginning the pass. 75 mi/hr 5 seconds after beginning the pass. What is the rate of acceleration of the car?What is the rate of acceleration of the car?

A)A) 10 m/s10 m/s B) -25 mi/hr/sec C) 25 B) -25 mi/hr/sec C) 25 mi/hr/secmi/hr/sec

D) 5 m/sD) 5 m/s22 E) 5 mi/hr/secE) 5 mi/hr/sec F) 10 m/sF) 10 m/s22

A car going 20 m/s (about 45 mph) is put into neutral and coasts to a complete stop. You have an accelerometer in the car and it shows you are decelerating at a rate of - 2 m/s2. How long does it take for the car to slow down to a speed of 10 m/s (22 mph)?

A)1 sec B) 2 sec

C) 5 sec D) 10 sec E) 40 sec

Anything with mass has a gravitational pull The larger the MASS of an object, the larger the gravitational pullThe closer you are, the greater the “g”

Galileo Galilee – Experimented with dropping different massed objects off the Tower of Pisa.

All objects fall at the same rate, regardless of mass – 9.8 m/s2

Isaac Newton – He did experiments that showed allThings with mass have gravity.

GravityGravity

Albert Einstein – Albert Einstein – Explained why there is gravity through his Explained why there is gravity through his

ideas of space and time.ideas of space and time.

Objects with mass bend the “fabric” of Objects with mass bend the “fabric” of space/time and create an attraction of space/time and create an attraction of other objects.other objects.

Anything in motion has a right to say it is at restAnything in motion has a right to say it is at rest

It depends on your frame of referenceIt depends on your frame of reference

How How fastfast an object is falling: an object is falling:

Velocity = Gravity x TimeVelocity = Gravity x Time

v = gtv = gt How How farfar an object falls: an object falls:

Distance = ½ gtDistance = ½ gt22

You are standing on top of your 6 meter spaceship on the moon (gravity: 2 m/s2). You drop something off the spaceship. How long does it take to hit the ground?

A) .5 s B) 1 s C) 1.5 s D) 2 s E) 2.5 s F) 3 s

A penny is dropped from the top of the IDS Tower in A penny is dropped from the top of the IDS Tower in Minneapolis (236 m). A penny is also dropped from the Minneapolis (236 m). A penny is also dropped from the Sears tower in Chicago (442 m). Ignoring air resistance, Sears tower in Chicago (442 m). Ignoring air resistance, how much faster is the penny dropped from the Sears how much faster is the penny dropped from the Sears Tower going when it hits the ground than the IDS tower Tower going when it hits the ground than the IDS tower penny.penny.

IDS Tower

Sears Tower

A)12.4 m/sB)25 m/sC)68 m/sD)93 m/sE)164 m/sF) 212.4 m/sG) I don’t know how

to solve this

If an object has in initial velocity going up or down If an object has in initial velocity going up or down as it goes into freefall, the equation changes just as it goes into freefall, the equation changes just a little.a little.

How How fastfast an object is going with an initial velocity is an object is going with an initial velocity is expressed as:expressed as:

Velocity = VelocityVelocity = Velocity initialinitial + gravity x time + gravity x time

V = VV = V00 + gt + gt A ball is thrown upward at 15 m/s. How fast is it going after 2 seconds?

A) 4.6 m/s B) -4.6 m/sC) neither of these

How How farfar an object goes that has an initial an object goes that has an initial velocity is expressed asvelocity is expressed as

Distance = VelocityDistance = Velocityinitialinitial x time + ½ gravity x time x time + ½ gravity x time22

d = Vd = V00t + ½ gtt + ½ gt22

A ball is thrown upward at 15 m/s. How high is it after 2 seconds?

About…A) 5m B) 8m C) 10m D) 12 m

Kinematic EquationsKinematic Equations

The equations used for freefall can also be used in lateral The equations used for freefall can also be used in lateral motion, substituting “g” for whatever acceleration is motion, substituting “g” for whatever acceleration is present.present.

In summary, these equations can solve any straight line In summary, these equations can solve any straight line motion:motion:

V = VV = V00 + at + at

X = ½ (VX = ½ (V00 + V) t + V) t

X = VX = V00t + ½ att + ½ at22

VV22 = V = V0022 + 2ax + 2ax

Responsible for changes in rates of falling Responsible for changes in rates of falling objectsobjects

A form of friction that gives off heat.A form of friction that gives off heat. When air resistance is negligible, objects When air resistance is negligible, objects

can be considered “free falling”can be considered “free falling”

Which stage is the object stopped?Which stage is the object stopped?

Where is the object accelerating?

What stage shows a constant speed?

What would the graphlook like if the object moved backward at Stage 6?

Punter Chris Kluwe of the Vikings Punter Chris Kluwe of the Vikings has a hang time of 4 seconds on has a hang time of 4 seconds on a punt. How high does it go?a punt. How high does it go?

A) 10m B) 20mC) 30mD) 80mE) 160m

How long does it take for a waterBalloon to fall to ground from 15meters (about 5 stories)

A) 1.7 sec B) 3 sec C) .86 sec D) 4.7 sec

A rocket is launched upward and reaches a velocity A rocket is launched upward and reaches a velocity of 200mph at the moment the engine quits. What of 200mph at the moment the engine quits. What is the approximate velocity of the rocket at 1 is the approximate velocity of the rocket at 1 second after the engine went out (#2)?second after the engine went out (#2)?

A) 0 mphB) 198 mphC) 200 mphD) 202 mph