# Newton's Laws of Motion on a helicopter

1. Sep 20, 2007

### brriney

1. The problem statement, all variables and given/known data

A 12000- kg helicopter is lifting a 4000- kg truck with an upward acceleration of 0.9 m/s2. Calculate the force the air exerts on the helicopter blades.

2. Relevant equations

F = ma

3. The attempt at a solution

2. Sep 20, 2007

### Astronuc

Staff Emeritus
Well the answer depends on whether the helicopter is hovering (stationary) or is also accelerating with the truck.

Let's assume the helicopter is hovering. It has a weight which is the product of its mass and the acceleration of gravity.

Now looking at the truck, it also has a weight which is the product of its mass and the acceleration due to gravity, but the helicopter is pulling it up with an additional acceleration of 0.9 m/s2, so one has to add that acceleration to the acceleration of gravity to get the combined force.

If the helicopter is also accelerating then one has to add that inertial acceleration to the acceleration of gravity.

g = 9.81 m/s2