Velocity and Acceleration Test Study Guide



Velocity and Acceleration Test Study Guide

You will need to know:

• The difference between distance and displacement

• How to draw or read a motion map (the dots) . . . . . .

• That velocity and speed are basically the same, but velocity has a direction

• How to read a distance / time graph

• How to read a velocity / time graph

• How to calculate the average velocity of a given timeframe

• How to use the formula for velocity to calculate velocity, distance or time

v = d

t

• How to calculate the acceleration of an object, or be able to use the formula for acceleration to find the unknown variable

a = vf-vi

t

Average velocity is the total distance divided by the total time (in a given time frame)

For example: If I gave you a graph like the one below and asked you to calculate the average velocity of Charlie’s run, you would take the total distance run and divide by the total time. V= 100m / 17 seconds = 5.88m/s

BUT if I asked you to calculate the average velocity for the first part of his run from start to 8 seconds, you would calculate v= 50m/8s = 6.25 m/s

[pic]

When looking at a velocity / time graph, you can calculate the acceleration by picking two points along the graph as your initial Vi and final Vf velocities (the one that is earlier in time is the initial, and the one later in time is the final)

Then you divide that by the amount of time that has passed during that segment

For example:

[pic]

In the graph above, if I asked: Calculate the acceleration for segment D-E, you would take the final velocity at E (5m/s) and subtract the velocity at D (0m/s), then divide by the time of that segment which is 5s.

5 - 0

a= 5

a= 1m/s2

Things to remember…

• Don’t forget to use the right units in your answer. Look at the word problem or data table for your units.

• Velocity is a rate, so you will always have some unit per time unit : m/s, km/hr, etc.

• Acceleration is a rate of velocity, so the time unit will usually be squared: km/hr2 m/s2 etc.

• Look at the graph to make sure you are reading a distance (position)/time graph or a

Velocity (speed)/time graph.

My website under the Staff Pages here at Glenn does have some of the notes and powerpoints for you to reference….so use that if it helps.

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