Question

A stone is projected vertically from the top of a tower 78.4 m with a velocity 29.4 m/s. Find the time taken by the stone to reach the foot of the tower.

Answer 1

Answer:

Here

it was thrown from a height

thus

u=0

h=78.4

a=g=9.8 (acceleration due to gravity)

t=?

According to the Second equation of motion,that is Position Time relation

We know

S=ut+1/2at²

here s=h (height)

and a=g

also u=0

that is

h=0×a+1/2at²

h=1/2gt²

t=√(2×78.4)/9.8

t=√156.8/9.8

t=√16

t=4

Therefore it took the stone 4 seconds to reach