1. 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

2. 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)

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

4. 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!

5. 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 = m/s2
v0 = 30 m/s
v = 0 m/s
(d0 = 0m)
d = ?

6. 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 = m/s2
ʋ = 0 m/s
d0 = 0 m

7. 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 = ?

8. 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)

9. 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

10. 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!)

11. 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) (-4.75)
d = -900/-9.5
d = 94.74

12. 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 = m
Use the Moving Man Simulation to check your answer.

13. 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)