A ball of mass $0.05$ kg moves horizontally at $8$ m/s. It is struck with a racquet causing it to travel at $18$ m/s in the opposite direction. Find the impulse imparted to the ball considering uncertainties in the given data.
My understanding is that $0.05$ means $0.050 \pm 0.005$, $8$ means $8.0 \pm 0.5$, and $18$ means $18.0 \pm 0.5$, taking uncertainties into consideration.
Mass: $m=0.050\pm0.005$ kg
Initial velocity: $\vec u = +8.0\pm 0.5 \vec i$ m/s
Final velocity: $\vec v = -18.0\pm 0.5 \vec i$ m/s
Q1: Is that correct?
My formula for Impulse is then $$\vec I = m(\vec v - \vec u)$$
I get max and min values for impulse of: $\vec I_{max}=-1.485 \vec i$ Ns, and $\vec I_{min}=-1.125 \vec i$ Ns.
Taking the mean and the range of these two values I get an answer of: $$\vec I = -1.305 \pm 0.18 \vec i Ns$$
Q2: I learned that a calculation can only be as accurate as the data used in the calculation. Some of the data here has only one significant figure. So how should I report/present my result? Should I round it up to something like $\vec I = -1.3 \pm 0.2$ Ns ? But why should I ? I mean the result above gives the entire range of possible values given the data. Even though the data may have only 1 significant figure the result seemingly can have many more. What is the standard procedure here?