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Kinematics. Average Acceleration. Variables. In addition to the variables previously used to calculate average velocity ( v avg ), we add one more: a- acceleration (m/s 2 ) a avg - average acceleration. Solving for acceleration. Acceleration can be found 2 ways:
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Kinematics Average Acceleration
Variables • In addition to the variables previously used to calculate average velocity (vavg), we add one more: • a- acceleration (m/s2) aavg- average acceleration
Solving for acceleration • Acceleration can be found 2 ways: • Graphically- read from a Velocity vs. Time graph • Mathematically- found using an equation
Graphically • Imagine a velocity vs time graph: • Consider the SLOPE of this line.
Graphically • The slope is Δv/Δt = (10m/s) / (5s) • Look at the UNITS of the slope…
Graphically Same units as acceleration.
Graphically The SLOPE of a VELOCITY vs. TIME graph represents the ACCELERATION of the moving object.
Mathematically • Formula: • The formula looks like the slope of the velocity vs. time graph: That is where it comes from.
Example • A shuttle bus slows down with an average acceleration of -1.8 m/s2. How long does it take the bus to slow from 9.0 m/s to a complete stop.
Example • A shuttle bus slows down with an average acceleration of -1.8 m/s2. How long does it take the bus to slow from 9.0 m/s to a complete stop. • Givens: a= -1.8 m/s2 vi= 9.0 m/s vf= 0 m/s (implied) • Unknown: t=?
Example • A shuttle bus slows down with an average acceleration of -1.8 m/s2. How long does it take the bus to slow from 9.0 m/s to a complete stop. • Givens: a= -1.8 m/s2 vi= 9.0 m/s vf= 0 m/s (implied) • Unknown: t=? • Formula:
Example • A shuttle bus slows down with an average acceleration of -1.8 m/s2. How long does it take the bus to slow from 9.0 m/s to a complete stop. • Givens: a= -1.8 m/s2 vi= 9.0 m/s vf= 0 m/s (implied) • Unknown: t=? • Formula:
Practice • Page 49, Practice B. • ALL units will be in meters, seconds, and m/s.