Download - Physics Review What do I need to know???. Variables Definition Types – Independent – Dependent
Physics Review
What do I need to know???
Variables
• Definition• Types– Independent– Dependent
Graphing
• Parts of a graph– Axis labels• Variables that go on each label
• Getting a straight line– y = mx + b• m = slope• b = y intercept
GraphingTime Distance
0 s 0 m
5 s 15 m
15 s 45 m
If you are given data….Graph it and then find the slope and intercept of the line
Pendulum Experiment
• Possible Variables– Length– Mass– Angle
• IV = your chosen variable• DV = time (pendulum period)• Variables that actually changed the period– Length
Pendulum Equation
• I will give it to you…• Remember how to use it– What is the period of a pendulum with a length of
2 m?
– What is the length of a pendulum that has a period of 2 seconds?
Vector vs. Scalar
• Scalar– Just a number, no direction.– Examples
• Speed
• Vector– Has both a direction and a magnitude.– Takes into account the direction and the magnitude.– Examples
• Acceleration and velocity
Speed
• Equation for speed– Speed = Δd/Δt
• A person walks 400 m in 2 minutes. What is their speed in m/s?
• How far does a person run if they walk at 7 mi/hr for 55 minutes?
Speed Calculations
• Speed is…– Total distance traveled = 27 + 14 = 41 miles– Total Time = 33 minutes = 0.55 hours– Speed = 41 miles / 0.55 hrs = 75 mi/hr
Yuma Eckley Wray
14 miles in 10 minutes
27 miles in 23 minutes
Velocity
• Equation for Velocity– Δd/Δt• but…you have to take into account the direction
• Two types– Instantaneous• At one specific time.
– Average• Over a period of time
Velocity Calculations
• Velocity is– Δd = 13 miles East– Δt = 41 minutes = 0.55 hrs– V = 13/ 0.55 = 24 mi / hr EAST
Yuma Eckley Wray
14 miles in 10 minutes
27 miles in 23 minutes
Finding Velocity From a Graph
• Velocity is from the position vs. time graph.
0 5 10 15 20 25 300
5
10
15
20
25
30
Position
Time (s)
Positi
on (m
)
Find the average velocity… For 0-25 seconds
For 0-10 seconds
Find the instantaneous velocity for…10 seconds
20 seconds
Acceleration
• Definition and Equation– ΔV /Δt
• Types– Instantaneous– Average
Finding Acceleration From a Graph
• Velocity is from the velocity vs. time graph.
Find the average acceleration… For 0-15 seconds
For 10-20 seconds
Find the instantaneous acceleration for…10 seconds
20 seconds
0 5 10 15 20 25 300
5
10
15
20
25
30
Velocity
Time (s)
Velo
city
(m/s
)
How all the graphs relate
• On the board…
Significant Figures
• Know the rules– Before the numbers
• Doesn’t Count
– Between the numbers• Always Counts
– After the Numbers• After the decimal
– Always counts
• Before the decimal– With a decimal (counts)– Without a decimal (doesn’t count)
Significant figures and Calculations
• The lower number of significant figures determines how many sig figs are in the answer
0.0090 x 100. =
100.0 x 12 =
3.00 x 0.002 =
Significant Figures and Sci. Notation
• Only significant numbers appear in the number part of scientific notation.
0.900 =
2.00 x 10. =
4.00 x 140 =
Metric
• Know the prefixes– Kilo, hecto, deca, deci, centi, milli
100 cm = _______ hm
1 kg = ________ cg
Conversions
• Always start with what you know over 1• Include Units• Remember, if you want units to cancel out you
have to have one on top of the fraction and one on the bottom of the fraction
1 mile = __________ inches
3 ft = __________ miles