How to Calculate the Uncertainty of time, period time/n, and Vmax of mass in the table?

Experiment 1, Part 2: Changing Mass

Data Collection Table 2: Varying Mass
Number of Oscillations (N): 10
Object Mass (g)	Object Mass (kg)	Trial 1 Time(s)	Trial 2 Time(s)	Trial 3 Time(s)	Uncertainty of Time (s)	Period (s) time/N	Vmaxof mass (m/s)
50	0.05	7.6	8.15	7.86
100	0.1	12.7	12.78	12.83
150	0.15	14.33	14.37	14.49
Bolt ( 23g)	0.023	6.16	6.10	6.2