Question

An object with mass 8.5kg is moving vertically upward with a velocity if 35m/s at a height of 100m above the ground.
Find the time the object takes to reach the ground

Thanks!!

Answer 1

Kinematics equation:
Δx = vi*Δt + (1/2)aΔt²

Here
Δt = elapsed time, in seconds
vi=initial velocity = +35 m/s
a=acceleration due to gravity = -9.8 m/s²
Δx=displacement = -100 m

-100=35Δt + (-9.8/2)Δt²
Solve by quadratic formula for Δt
and reject negative root:
Δt
= (5√65+25)/7
= 9.88 s (approx.)