Final answer:
To determine the time the stunt man was in the air, we use his horizontal distance traveled and the physics of free fall. The time is found by dividing the distance by the constant horizontal velocity, which we can calculate using the free fall formula for the vertical motion.
Step-by-step explanation:
To calculate how long the stunt man was in the air after being fired out of the cannon, we need to consider only the horizontal motion because he was shot horizontally. Since there is no horizontal acceleration (assuming no air resistance), the horizontal velocity (v) can be calculated by dividing the horizontal distance (d) by the time (t) in the air, using the formula d = v * t. Given that the horizontal distance covered is 150 meters, and the stunt man was fired from a cannon situated 20 meters above ground, we can find the time in the air by using the equation of motion in free fall for the vertical component to first find the time it takes to fall from 20 meters, which is t = sqrt(2h/g), where h is the height (20m) and g is the acceleration due to gravity (9.8 m/s2).