Question

helicopter at rest, uniformly accelerates upwards. After 25s flare fired horizontally from the heli. flare measured to 8s to reach the ground.
a)What is the acceleration of the helicopter
b) height of the helicopter the instant the flare reached the ground.

Answer 1

The time of flare falling down t=8 s = >
The flare fell from the height h=gt²/2 =9.8•8²/2=313.6 m
since the time of accelerated helicopter motion is t1 =25 s,
its acceleration was
a=2h/t1²= 2•313.6/25²=1 m/s²
The helicopter gets off by the height Δh during 8 seconds,
Δh=a•t1²/2 =1•8²/2 =32 m
H=h+ Δh=313.6+32=345.6m