rocket experiment analysis

[jnimagine]

we fired off a rocket in physics class and we have to write a report about it.
I found out that the height of the rocket calculated using formulas was very off from the real height of the rocket figured out by calculating the tangent of the angle of altitude. (there was an altitude person who measured the angle to the height of the rocket when it was fired off) That angle was 40degrees. The height I got using formulas ( first figuring out max kinetic energy then gravitational energy, then total energy, then the height) was 1127 while the one using distance measured from the rocket's highest point to where the altitude was measured and tan of 40 was 82:eek: yah i know the two numbers aren't close at all.
So we have to discuss why the result is so off. Reasons other than things like human errors... maybe something like wind??? i just can't figure it out well...T.T

Thank you for your help

[student85]

how did you measure inicial velocity?
Remember too that not all kinetic energy is transferred to potencial energy due to the loses in real life experiments.

[Danger]

Even excluding wind, there's a lot of aerodynamic drag, friction from the launch pad (if you use a stand-up guide that the rocket runs up), and just general efficiency losses because the numbers are usually based upon ideal circumstances which aren't encountered in real life.

[3trQN]

Work with your uncertainties and errors, see if its within range. no use talking absolutes.

[jnimagine]

well we just assumed the initial velocity as 0m/s...

[jnimagine]

how did you measure inicial velocity?
Remember too that not all kinetic energy is transferred to potencial energy due to the loses in real life experiments.

hey student85
thanks for the reply
um... we just assumed the initial velocity as 0m/s...
could u explain more about kinetic not always changing to potential??
where would the energy go if it doesn't get transferred to potential??

[jnimagine]

Even excluding wind, there's a lot of aerodynamic drag, friction from the launch pad (if you use a stand-up guide that the rocket runs up), and just general efficiency losses because the numbers are usually based upon ideal circumstances which aren't encountered in real life.

ya we used the stand-up guide launch pad
so if there's friction formed there, how would u explain that friction caused the height to be different?
and um.... about aerodynamic drag... do u mean just the gravity that's pulling down on the rocket?
and also like student 85 said what are some examples of efficiency losses? and how would this make the calculation of the height to be so wrong?? :confused:
i know i'm posting thousand questions at u guys
but I'd really appreciate it if u could answer these questions for me
thanx~ :smile: