One device used for throwing spears is an atlatl. This device was used by human hunters over 20000 years before the invention of the bow ad arrow. It effectively increases the length of the hunter's arm allowing a spear to be thrown further than it could be by hand alone.

A spear is launched from 2m above the ground with a velocity of 22.5ms-1 at an angle of 38 to the horizontal. It strikes a distant target which is also 2m above the ground.The initial vertical component of the spear's velocity is about 14ms-1.

Show that time taken for the spear to reach the target is about 3s. (Ignore the effect of air resistance)

PLEase please help i am really confused

Vo = 22.5m/s[38o].

Xo = 22.5*Cos38 = 17.7 m/s.
Yo = 22.5*sin38 = 13.9 m/s.

Y = Yo + g*Tr = 0 @ max ht.
14 + (-9.8)*Tr = 0
Tr = 1.43 s. = Rise time.

Tf = Tr = 1.43 s. = Fall time.

Tr+Tf = 1.43 + 1.43 = 2.86 s. or about 3 s.