Acceleration

SCI10-FM3

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Investigate and represent the motion of objects that undergo acceleration.

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Acceleration

• When speed is not constant » may be changing slowly or rapidly
• Changing » may be increasing or decreasing
• Acceleration describes all situations when speed is changing

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Acceleration

Acceleration (a) » the rate of change in speed

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Acceleration is calculated by the ratio of the change in speed (Δv) to the time interval (Δt) during which this change has occurred.

Acceleration

a

=

Δv

Δt

Acceleration

a = Δv / Δt

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Constant acceleration » ratio remains constant throughout the acceleration.

The same change in speed (Δv) occurs in each equal interval of time (Δt)

Sample Problem

This car can speed up from a rest (0 m/s) to 30 m/s in 5 seconds. Calculate average acceleration.

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Δv = 30 m/s

Δt = 5.0 s

a_av = ?

a_av = Δv / Δt

a_av = (30 m/s) / 5 s

a_av = 6.0 m/s

s

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Average Acceleration

A_av = 6.0 m/s

s

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In other words, you will increase your speed by an average of 6.0 m/s at the end of the 1^st second; 12.0 m/s at the end of the 2^nd second; and 18.0 m/s at the end of the 3^rd second

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Average Acceleration

Average acceleration can also be written as:

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a_av = 6.0 m/s ²

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