Question

A projectile is fired straight upward from the Earth's surface with an initial speed of 33.3m/sec. What is it's speed after 2.8secs?

Answer 1

let's write it as an equation

speed in m/sec (s) = 33.3 -9.81s

speed in m/sec (2.8) = 33.3 -9.81*2.8 = 5.832

9.81 is the deceleration due to earth's gravity.

the speed changes that ammount per second.