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Kinematics Review and Study Guide

• When solving kinematics problems, first identify what type of problem you are solving (use your flow chart to help you decide)

• Always remember SIGNS and unit conversions!!!

Uniform Motion (Constant Velocity)

• v = speed (m/s)

• [pic] = velocity (m/s)

• d = distance (m)

• [pic]= displacement (m)

• t = time (m)

• For constant/uniform velocity only, use [pic]

• average speed = [pic] =[pic]

• average velocity = [pic] = [pic]

Uniform Accelerated Motion (Constant Acceleration)

• a = acceleration (m/s2)

• For acceleration problems (ie. a change in velocity problem), need to use one of the following five equations (Note: cannot use [pic]for acceleration problems!!)

o [pic]=[pic]

o [pic]

o [pic]

o [pic]

o [pic]

• These formulas are identical to what is on the formula sheet

Free Falling Objects

• Has to be in the air to be considered free falling

• Acceleration for these problems is always 9.81m/s2 and is a constant value that is always directed down toward the center of the Earth

• Since these are still acceleration problems, use one of the five equations listed above (do not use [pic], this is only for constant velocity!!!)

o Max. height occurs when the vertical velocity is 0.0m/s and for symmetrical problems, occurs at half time

• At the same height, the object has the same speed as it did going up as it does going down

Graphing

• Ned to be able to analyze a distance vs. time graph and a velocity vs. time graph

• When asked a calculation question for a graph, consider using one of the 3 options

o Looking at what the axes represent

o Consider what the calculated slope represents [pic]

o Consider what the calculated area under the graph represent

Two-Dimensional Kinematics

• For vectors that are perpendicular to each other, follow the last two steps (steps 3 and 4) listed below

• For vectors that are not perpendicular to each other, follow all four steps listed below

o Step 1: Draw grid lines on each break and break each vector into its x and y components

o Step 2: Calculate the xtotal and ytotal

o Step 3: Re-draw a new triangle using tip-to-tail method with your xtotal and ytotal and use Pythagorean’s Theorem to calculate the resultant

o Step 4: Find the direction/angle

Projectile Motion

• The horizontal component is uniform motion

o Always use [pic]

• The vertical component is uniform acceleration

o Acceleration is 9.81m/s2 because it is a free falling object

o Need to use one of the five acceleration equations

o Remember at maximum height, v=0.0m/s

o Also remember that at the same height, the object has the same speed as it did going up as it does going down

• Need to solve for time in either the horizontal or vertical component first

o Time is the same for the x component and the y component

Relative Motion Question

• Time is the same on all sides of the triangle

• Can only use trig. and Pythagoreans Theorem if all units are the same

• Be sure to keep all the vertical, horizontal, or diagonal information separate (except for time)

o When using [pic], need to be using all vertical information only (or all horizontal information only or all diagonal information only). For example, you cannot use a vertical distance and a horizontal speed to calculate time.

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