A cannon fires a shell straight upward; 1.8 s after it is launched, the shell is moving upward with a speed of 17 m/s. Assuming air resistance is negligible, find the speed (magnitude of velocity) in meters per second of the shell at launch and 5.5 s after the launch

To solve this problem we will apply the concepts of acceleration according to the laws of kinetics. Acceleration can be defined as the change in velocity per unit time, that is,

Here,

v = Final velocity

u = Initial velocity

t = Time

Rearranging to find the initial velocity,

Now the acceleration is equal to the gravity, then,

The velocity of the shell at 5.5s after the launch is,

Therefore the magnitude of the velocity of the shell at 5.5s is -19.26m/s

answer: the answer is a