MOTION

Main Idea: Motion Acceleration

Learning Goals Define acceleration. Calculate acceleration using the formula.

Acceleration Key Question: What is acceleration?

Acceleration Acceleration is the rate at which your speed (or velocity) changes.

Acceleration If your speed increases by 1 meter per second (m/s) for each second, then your acceleration is 1 m/s per second or 1m/s2.

Acceleration If the hill is steeper, the acceleration is greater.

Acceleration There is zero acceleration at constant speed because the speed does not change.

Acceleration Speed and acceleration are not the same thing. You can be moving and have no acceleration (think cruise control). A falling object begins accelerating the instant it is released.

Acceleration and direction Acceleration occurs whenever there is a change in speed, direction, or both.

Acceleration and direction A car driving around a curve at a constant speed is accelerating because its direction is changing.

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Acceleration Acceleration describes how quickly speed changes. Acceleration is the change in speed divided by the change in time.

A strong wind increases its speed to 4 m/s in 3 s. Solving Problems A sailboat moves at 1 m/s. A strong wind increases its speed to 4 m/s in 3 s. Calculate acceleration.

= 1 m/s2 Solving Problems Looking for: …acceleration Given: …v1 = 1 m/s; v2 = 4 m/s; time = 3 s Relationships: a = v2 – v1/t Solution: a = (4 m/s – 1 m/s)/ 3 s = 1 m/s2