How high will a cannonball reach if fired straight up out of a cannon at an initial upward velocity of 120m/s?

720 m

Explanation:

Taking the upward direction as positive

We are given:

Initial vertical velocity of the cannonball = 120 m/s

Vertical acceleration of the cannonball = -10 m/s²

Final velocity of the Cannonball = 0 m/s [at the maximum height, the velocity of the ball will be 0 m/s for a moment]

Maximum height of the ball:

v² - u² = 2as                                 [Third equation of motion]

replacing the variables (s is the maximum height)

(0)² - (120)² = 2(-10)(s)

-14400 = -20s

s = -14400 / -20                           [Dividing both sides by -20]

s = 720 m

Hence, the maximum height of the Cannonball fired vertically at a velocity of 120 m/s is 720 m