How to solve word problem in Physics

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How to solve word problemin Physics

• Average Acceleration Problem

By Nerima Pasic
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• At t 5 s an object is traveling at 5m/s.
• At t 8s its velocity is 1m/s.
• Find the average acceleration for this interval.

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Strategy

• What does problem ask for?
• The problem asks for average acceleration under
  certain conditions.

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What is given?

• Time t15 s
• Velocity v15m/s
• Time t2 8 s
• Velocity v2 -1m/ s

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What is equation for average acceleration?

• aave (v2-v1) / (t2 t1 )

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Lets work from left to right!
aave (v2-v1) / (t2 t1 )
This equation asks for v2
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What is v2 ?
It is the final velocity, which the problem
states is v2 -1m/ s
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Working left to right equation now asks for v1
aave (v2-v1) / (t2 t1 )
What is v1?
Its initial velocity which the problem states is
V15m/s.
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Working top down, the equation next asks for
t2.
What is it?
aave (v2-v1) / (t2 t1 )
It is final stopwatch reading.
The problem states that this is t2 8 s
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Continuing left-right the equation next asks for
t1 .
aave (v2-v1) / (t2 t1 )
Again, What is it?
It is initial stopwatch reading, which the
problem states is t1 5s.
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Lets go back and see now what was given?

• Time t15 s ..initial time
• Velocity v15m/s..initial velocity
• Time t2 8 sfinal time
• Velocity v2 -1m/ s..final velocity

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Substituting these results in the starting
equation gives

• aave (-1m/s)-(5m/s)/(8s-5s)
• Factoring units gives aave (-1-5)m/(8-5) s/s
• aave (-6m)/(3s/s)
• aave 2m/s/s or aave 2m/s2
• (s2 means s x s second squared)
• Average acceleration is
• 2 meter per second-every second.