Hey everyone, this is my first time using the PF, so please excuse me if I am not following the usual method for posting questions. Also, its my first time using Latex spelling, so i may very well have slaughtered it. :yuck:(adsbygoogle = window.adsbygoogle || []).push({});

I have access to 5 equations...

1.[tex]v=v_0+a t[/tex]

2.[tex]\Delta X=v_0 t+/frac{1} {2} a t^2[/tex]

3.[tex]v^2=v_0^2 +2a delta x[/tex]

4.[tex]\Delta X=/frac{1}{2}(v_0 + v)t[/tex]

5.[tex]\Delta X=v t - /frac{1} {2}a t^2[/tex]

My teacher has given us 2 problems, and the only help he gave was "use the formulas!".

The problems are as follows...

1. A rifle is fired and the bullet is accelerated from rest through the barrel which is 1.00m long. If the bullet leaves the barrel at a speed of 600m/s, calculate its acceleration.

2. A balloon is rising at a steady rate of 29.4 m/s. A stone falls from the balloon and reaches the ground in 20.0 seconds. At the instant the stone reaches the ground, how far is the balloon above it?

I have thought about both of the equations and I have come up with the following...

1. I really have no idea on this one...The only idea I have been able to come up with is if it leaves the 1m long barrel at a speed of 600m/s then it took 1/600th of a second to travel the length of the barrel.

2. I don't know which formula to use on this one, but I did some different kind of work on it. If the balloon is rising at 29.4 m/s and it takes the stone 20 seconds to fall to the ground, wouldn't I just be able to say 29.4 m/s * 20?

Help on these would be extremely appreciative. :!!)

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# Homework Help: Acceleration/Gravity problems

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