# Acceleration of the helicopter as it starts to rise!

anlenemilk

## Homework Statement

At take off, the rotor blades of a helicopter propel 2400 kg of air vertically downwards each second. The air, intially at rest, is given a speed of 11ms^-1
QN: the mass of the helicopter is 2500 kg. Find the acceleration of the helicopter as it starts to rise

## Homework Equations

<F>=Change in momentum /change in time
Fnet=ma

## The Attempt at a Solution

<F>=Change in momentum /change in time
= (2400*11-0)/1= 26400N
26400-2500(9.81)=(2500)a
a=0.75ms^-2

I have no idea how to get this answer! HELP ME! THANK YOU VERY MUCH