Announcements 1 No homework due tomorrow a Would be an excellent evening to study for and or take the exam 2 Exam 1 starts today a Available in Testing Center from Tues Sept 16 10 15 am up to Monday Sep 22 closing time i If you pick up your exam after 5 pm you ll have a late fee b Covers Ch 2 3 homeworks 1 3 c There s a 3 hour time limit i Last year s Exam 1 1 Students took an average of 1 5 hours 2 Some took less than 1 hour 3 Some took the full 3 hours ii This year s Exam 1 will be a little harder d Advice i Take time and space to draw diagrams ii Show all your work on the exam papers iii Write your numerical answers in the blanks iv Circle the correct choice v Then transfer your answers onto your bubble sheet e Note card i I will not give you any formulas on the exam ii I will give any constants like g 9 8 m s2 or conversion factors that you need iii Write anything else you want on a 3 5 note card front back Handwritten only f Calculators i They are allowed any type ii Be sure your calculator has at least basic scientific functions such as trig exponents etc g Last year s Exam 1 is posted on the web site along with solutions i Don t look at the solutions until you ve worked the exam or you won t find out where you are weak It s easy to fool yourself h Things to study i HW problems ii In class problems clicker quizzes problems iii Last year s exam iv Concepts from lectures demos v Other problems textbook other books etc Colton Lecture 5 9 16 08 pg 1 Colton Lecture 5 9 16 08 pg 2 Exam format Formulas Review The following graph is of velocity vs time v t of a car moving along a road and right is positive The graph shows that the car is 1 a speeding up b slowing down c staying at constant speed and moving to the 2 a right b left with acceleration to the 3 a right b left and the acceleration is 4 a increasing in magnitude b decreasing in magnitude c constant Definitions Final exam you will be expected to know these x v ave v t v instantan slope of tangent line of x vs t graph a ave a v t a instantan slope of tangent line of v vs t graph v is to the right Trigonometry definitions Final exam you will be expected to know these opposite hypotenuse adjacent cos hypotenuse opposite tan adjacent sin t A jet plane lands with a speed of 50 m s and can decelerate slow down at a maximum acceleration magnitude of 7 m s2 as it comes to rest From the instant the plane touches the runway what is the minimum time needed before it can come to rest 11 a less than 7 0 s b between 7 0 and 7 1 s c between 7 1 and 7 2 s d between 7 2 and 7 3 s e between 7 3 and 7 4 s f between 7 4 and 7 5 s g between 7 5 and 7 6 s h more than 7 6 s Quadratic formula Final exam I will give you this If ax 2 bx c 0 x b b 2 4ac 2a These bubble sheets have 10 bubbles per question Colton Lecture 5 9 16 08 pg 3 Colton Lecture 5 9 16 08 pg 4 Kinematic formulas for constant a Final exam I will give you these v vf vave i 2 v vo at x xo vot 1 2 at 2 v f 2 vo 2 2a x Kinematic formulas applied to projectiles Final exam I will not give you these just plug in ax 0 and ay g to the regular kinematic formulas which I will give you x direction vx vox x xo vox t y direction v y voy gt y yo voy t 1 2 gt 2 v y 2 voy 2 2 g y Concepts Review 1 Trig need to know how sin cos and tan work 2 Motion a Displacement b Velocity and speed c Acceleration always in direction of force d How to interpret x t v t and a t graphs i slopes connect them e Average vs Instantaneous 3 Kinematic equations a Take your time i Draw pictures choose direction 1 Write given info on picture properly labeled example vf 10 m s 2 Write missing info on picture also labeled example x ii Think about which equations describe the motion iii Write down the most relevant equations symbolically iv Plug numbers into your equations see what they tell you Colton Lecture 5 9 16 08 pg 5 Colton Lecture 5 9 16 08 pg 6 v Do algebra carefully vi Plug numbers into calculator twice b Problems can be done more than one way it doesn t hurt to check your work with other eqns 6 Relative motion a One dimension it s easy to figure out just add or subtract speeds b 2 dimensions draw vectors and write the vector equation vac vab vbc with a b and c being objects from the problem Then be sure your work components agrees with it 4 Adding Vectors a Graphically always do b With components i Use cos sin to get x and y shadows ii Add x and y components separately to get components of final vector iii Magnitude of final vector Pythagorean thm iv Angle of final vector tangent 5 Free fall projectiles a Two sets of kinematic equations x and y i ax 0 ii If up positive then ay g 9 8 m s2 b If initial velocity at an angle divide v0 into x and y components c If range type problem think about which coordinate sets the time i Solve for time ii Plug into other coordinate s equation s Colton Lecture 5 9 16 08 pg 7 Colton Lecture 5 9 16 08 pg 8 Some concepts from last lecture Maximum range Sally and Bob each throw a rock horizontally from a cliff Sally throws her rock hard Bob throws his more easily Warmup Neglecting air resistance at what angle should you throw a ball on a flat field in order to get the maximum range a 30 b 45 c 60 d It depends on the initial speed Clicker quiz Which spends the longest time falling a Sally s b Bob s c same Clicker quiz Which rock is going fastest vector magnitude just before it hits the ground a Sally s b Bob s c same We re also neglecting height of person that could have a slight effect What if you do worry about air resistance Simulation Sally throws a rock horizontally from a cliff Bob throws his at an angle above horizontal They throw the same speed http phet colorado edu new simulations …