Question

an arrow was shot vertically upward from the ground. it fell down 5 seconds later. find its
a. initial velocity
b. maximum height reach

Answer 1

An arrow was shot vertically upward from the ground. it fell down 5 seconds later.

Total time of flight = 5 sec
Time of upward flight = 5/2 = 2.5 sec

Thus, to reach maximum height
t = 2.5s
g = -10 m/s^2
v = 0 ( at maximum height)
u = ?
h = ?

v = u + gt
0 = u - 10×2.5
0 = u - 25
u = 25 m/s

Max height, h = u^2/2g
h = 25^2/(2×10)
h = 625/20
h = 31.25 m

Initial velocity is 25 m/s and maximum height reached is 31.25m

(You can try taking g as 9.8 m/s^2 if you like.)

Hope it helps!

Answer 2

a. u= 25 m/s

b. h= 31.25 m