If a helicopter's mass if 4500kg and the net force onit is 18000 N upward what is its acceleration?

a = - 5.81 [m/s^2]

Explanation:

Using newton's second law, which tells us that the sum of forces is equal to the product of mass by acceleration, we can find acceleration. The forces acting are the weight of the helicopter and the lifting force.

W - Lf = m * a

W = weight of the helicopter [N]

Lf = lifting force = [N]

m = mass of the helicopter [kg]

a = acceleration [m/s^2]

- (4500*9.81) + 18000 = 4500 * a

a = - 5.81 [m/s^2]

The negative sign tells us that the helicopter is slowing down.