Warm-up 10/16: 1. What’s the difference between distance and displacement? 2. What’s the difference between speed and velocity? Variables that have an amount AND a direction are called vectors Variables that only have an amount are called scalars

Update Formula Chart: Put a v (for vector) next to every vector Put an s (for scalar) next to every scalar Add 4 equations - I’ll give you the equation, you can fill out the rest later: d = d0 + ʋ0t + ½ at2 d = d0 + ½(ʋ + ʋ0)t ʋ = ʋ0 + at ʋ2 = ʋ02 + 2a(d - d0)

Notes: Kinematics Essential question: How do we solve kinematics problems? Using SKUFWUNA!

What is SKUFWUNA? S – Sketch K – Known U – Unknown F – Formula Draw a picture based on the problem – including ALL info from the problem K – Known Write down the known amounts given in the problem – include the variable, the amount, and the units U – Unknown What are you trying to figure out? F – Formula Pick one from the formula chart. W – Working Equation Rearrange the equation so that your unknown is by itself on one side U – Units Plug the units into your working equation so you can make sure you did it right N – Numbers Plug the numbers into your working equation A – Answer Write your final answer!

Example: Moving Man Problems #2 A man driving a car traveling at 30m/s slams on the brakes and decelerates at 4.75 m/s2. How far does the car travel before it stops? S – sketch: a = -4.75 m/s2 v0 = 30 m/s v = 0 m/s (d0 = 0m) d = ?

Example: Moving Man Problems #2 A man driving a car traveling at 30m/s slams on the brakes and decelerates at 4.75 m/s2. How far does the car travel before it stops? K – known (symbol = # units) ʋ0 = 30 m/s a = -4.75 m/s2 ʋ = 0 m/s d0 = 0 m

Example: Moving Man Problems #2 A man driving a car traveling at 30m/s slams on the brakes and decelerates at 4.75 m/s2. How far does the car travel before it stops? U – Unknown d = ?

Example: Moving Man Problems #2 A man driving a car traveling at 30m/s slams on the brakes and decelerates at 4.75 m/s2. How far does the car travel before it stops? F – Formula Choose an equation from your formula containing the unknown and the knowns v2= v02 + 2a(d – d0)

Example: Moving Man Problems #2 A man driving a car traveling at 30m/s slams on the brakes and decelerates at 4.75 m/s2. How far does the car travel before it stops? W – working equation We need an equation that looks like d = Subtract v02 from both sides: v2 - v02 = 2a(d – d0) Divide both sides by 2a: (v2 - v02 )/ 2a = d – d0 Add d0 to both sides: d = (v2 - v02 )/ 2a + d0

Example: Moving Man Problems #2 A man driving a car traveling at 30m/s slams on the brakes and decelerates at 4.75 m/s2. How far does the car travel before it stops? U - units Solve your working equation with units only: d = (v2 - v02 )/ 2a + d0 m = (m2/s2 – m2/s2) + m m/s2 m = m + m m = m (check!)

Example: Moving Man Problems #2 A man driving a car traveling at 30m/s slams on the brakes and decelerates at 4.75 m/s2. How far does the car travel before it stops? N - numbers Solve your working equation with numbers: d = (v2 - v02 )/ 2a + d0 d = (02 – 302) + 0 2(-4.75) d = -900/-9.5 d = 94.74

Example: Moving Man Problems #2 A man driving a car traveling at 30m/s slams on the brakes and decelerates at 4.75 m/s2. How far does the car travel before it stops? A - Answer Write the Number and the Units together: d = 94.74 m Use the Moving Man Simulation to check your answer.

Important!!! You MUST show each step to get credit for the problem – even if you can do it in your head. Writing down the answer only will earn you a grade of 13. Out of 100. (After all, you can get the answer from the phET simulation – I need to know you can figure it out on your own)