# Relative Velocity Help!

"A helicopter is flying horizontally at 8.1 m/s and an altitude of 16 m when a package of emergency medical supplies is ejected horizontally backward with a speed of 13 m/s relative to the helicopter. Ignoring air resistance, what is the horizontal distance between the package and the helicopter when the package hits the ground?"

Any help at how to tackle this problem would be appreciated. I know it involves using a string of kinematic equations, but I'm having trouble with the velocity.

## Answers and Replies

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Well, if the helicopter were moving 100 m/s relative to Earth and shot the package at the same speed as before (13 m/s relative to itself), how would the distance change?

mcjohnst said:
"A helicopter is flying horizontally at 8.1 m/s and an altitude of 16 m when a package of emergency medical supplies is ejected horizontally backward with a speed of 13 m/s relative to the helicopter. Ignoring air resistance, what is the horizontal distance between the package and the helicopter when the package hits the ground?"

Any help at how to tackle this problem would be appreciated. I know it involves using a string of kinematic equations, but I'm having trouble with the velocity.

well its quite simple. ... take the vel of package in the backward hor. dir to b v=8.1+13=21.1m/s
H=16m
16=1/2*9.8*t*t evaluate t from this eqn.
d1=diatance travelled by the package in the hor. dir=v*t
d2=dist. travelled by the helicopter in the hor. dir.=8.1*t
hor. dist. bet the two when the package hits ground=d1+d2.

bye