How Do You Calculate Speed and Uncertainty with Given Measurements?

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To calculate speed and uncertainty, the formula v = d/t is used, where distance is 228 cm with an uncertainty of ±0.5 cm and time is 2.99 s with an uncertainty of ±0.5 s. The user conducted 15 trials, yielding a total speed of 44.99 s, leading to an average speed of 2.99 m/s. The user attempted to calculate the percentage uncertainties for both distance and time, resulting in confusion over the final speed calculation. Assistance is sought to clarify the correct method for determining speed and its associated uncertainties.
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Homework Statement


Hey there, I need some help with uncertainties and how to find the speed of a moving object. I have tried to solve the problem several times but my answer seems to be wrong.

Formula for speed : v=d/t
My uncertainties: 0.5cm (distance) and 0.5s for time. The uncertainties were measured with the same analog.
I did the experiment 15 times and got different speed result of the object each time. The total sum of the speeds ( 15 trials) was 44.99s. The average of that is 2.99 (15/44.99)
Oh and my measuring device was 228cm long (exact)

I need to find out the speed and the uncertainties
If I missed any detail please please let me know
PLEASE HELP! I'am very frustrated right now..=S


Homework Equations



Formula to use : v=d/t

The Attempt at a Solution



v=d/t
= (228 +\- 0.5)m/(2.99+\- 0.5)s
228 divided by 0.5 = 456%
2.99 divided by 0.5= 5.78%
456% +5.78%=461.98%

so now 461.98% * 76.2 ( which I got by diving 288 and 2.99)
my final answer was v=76.25m? +\- 39%..
I'am confused..
 
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Actually spend hours on trying to solve this :S
Help will be greatly appreciated!
 
anyone?
 
Check out this site here: http://www.rit.edu/cos/uphysics/uncertainties/Uncertaintiespart2.html
 
Last edited by a moderator:
Okey, thanks
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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