The air cannon is used to shoot an object upwards at 90 degrees to the horizontal. It takes 6.76 seconds to travel 6 m.
Use the formula relating distance, time, acceleration and time `s = u*t + (1/2)*a*t^2` where s is the distance traveled in time t if the initial velocity is u and the acceleration is a.
The values given in the problem are s = 6 m, t = 6.76 s, the acceleration is that due to gravity and equal to 9.8 m/s^2 in the downward direction; u has to be determined.
=> `6 = u*6.76 - (1/2)*9.8*6.76^2`
=> `u ~~ 34.01` m/s
The velocity with which the object is shot upwards is approximately 34.01 m/s