during world war I, mortars were fired from trtenches 3 feet down. The mortars had a velocity of 150ft/s. determine how long it will take for the mortar shelf to strike its target.

Solution:

h=Vt-1/2gt^2

3=150t-16t^2

t=0.02s

So it takes 0.02 seconds for the mortar shelf to strike its target