WEBVTT

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Here is the problem: An object speeds up from 4 m/s to 12 m/s over 80 m. Find its acceleration and the time taken.

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Find acceleration a and time t for motion in a straight line with constant acceleration.

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List the known quantities. Unknown: acceleration a and time t.

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Time from the average velocity.

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Acceleration.

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So the answer is a equals 0.8 m/s squared, t equals 10 s.

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With constant acceleration, any three of displacement, initial velocity, final velocity, acceleration and time fix the other two. Each pair of unknowns is solved with the equation that does not contain the other unknown.

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Check v squared equals u squared plus 2as: 144 equals 144.