weight of air soft pellet affect speed?

[BaiAle9888]

In my science fair project, I am trying to determine if the weight of an air soft BB affects the speed, measured by the time it takes to hit the target. I am using 2 different air soft BBs (12g and 20g) shot from the same air soft gun at distances of 25', 50', and 75'. I am doing all shooting on the same day so that air movement is the same for all measurement. I am resting the gun on a table so that the angle is the same for all trials. I will do each 10 times and take the average. Am I on the right track? Any suggestions on procedure?

[kevala]

In my science fair project, I am trying to determine if the weight of an air soft BB affects the speed, measured by the time it takes to hit the target. I am using 2 different air soft BBs (12g and 20g) shot from the same air soft gun at distances of 25', 50', and 75'. I am doing all shooting on the same day so that air movement is the same for all measurement. I am resting the gun on a table so that the angle is the same for all trials. I will do each 10 times and take the average. Am I on the right track? Any suggestions on procedure?

Sound like an awesome project! Your varibles sound good but is the table on flat ground and are the BB guns going to placed in the same spot if so great! Good luck.

Hope that helps,
kev

[kevala]

In my science fair project, I am trying to determine if the weight of an air soft BB affects the speed, measured by the time it takes to hit the target. I am using 2 different air soft BBs (12g and 20g) shot from the same air soft gun at distances of 25', 50', and 75'. I am doing all shooting on the same day so that air movement is the same for all measurement. I am resting the gun on a table so that the angle is the same for all trials. I will do each 10 times and take the average. Am I on the right track? Any suggestions on procedure?

Sound like an awesome project! Your varibles sound good but is the table on flat ground and are the BB guns going to placed in the same spot if so great! Good luck.

Hope that helps,
kev

[deleted-71631]

This certainly sounds like a good experiment and your description of the test setup
appears to be sound and well thought-out --

For purposes of hypothesizing possible test results, you may want to take a look
at the physics aspects of this special case, ballistic flight dominated by aerodynamic
drag and weight. The "ballistic coefficient" is an engineering parameter, weight
divided by the product of drag coefficient times surface area. A writeup on
ballistic coefficient:

http://en.wikipedia.org/wiki/Ballistic_coefficient

In your test as described, it appears that drag coefficient and surface area will be the
same, or very similar, for the two categories of pellets. Pellet weight will thus be
your primary independent variable. A reasonable hypothesis for you to consider,
based on ballistic coefficient explanations, is that the heavier pellets will accelerate
faster and maintain velocity longer, resulting in shorter flight times to the target.
But will your test results support this hypothesis, based on your particular test setups,
that is the question - and the challenge!

It may be worth measuring the error distribution (miss distances) as the pellets hit the target -
you may find that the heavier BC pellets have a tighter shot pattern due to their higher
velocities.

Speaking of other possible error considerations, be aware that manual stopwatch measurements will
introduce a measurement error, and you should take this into consideration when evaluating
your experiment results.

Good luck with your project, it sounds like you'll be able to make some interesting observations!

Peter Young

[LizzyW]

How do you plan on measuring the speed? I would think either a radar gun or a high speed video camera would work. But another way to measure may be where the airsoft bb hits the target. If the gun is immobilized and the only variable that changes is the distance to the target then one may hypothesize that the mark or hole the airsoft bb will be lower or higher based on the weight and distance.

Miss Lizzy
3rd Grade Science Teacher