2. A helicopter on a landing pad weighs 2000 newtons. As the helicopter
begin to turn, they push air downward with increasing force. When will
helicopter lift off the ground?

When the upward force exerted by the air will be larger than 2000 N

Explanation:

There are two forces acting on the helicopter:

- The weight of the helicopter, W, of magnitude

W = 2000 N

In the downward direction;

- The force exerted by the air on the helicopter, R, in the upward direction

According to Newton's second law of motion, the net force on the helicopter is equal to the product of its mass (m) and its acceleration (a), so we can write

where (R-W) is the net force on the helicopter.

In order for the helicopter to lift off the ground, the acceleration must be non-zero (and positive); this means that the term

R - W

must be positive.

Therefore, it must be

R > W

So, the magnitude of the force due to the air must be larger than the magnitude of the weight of the helicopter, 2000 N.

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