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**Ant** Question:

A Balloon of mass 490Kg is descending at a speed of 5 m/s with an acceleration of 0.2m/s^2. What mass must be thrown out to reduce the acell to zero.

I keep on getting an incorrect answer, but I'm not sure where I'm going wrong.

Here is how I am (trying) to work out the solution.

T.F = ma

mg - Upwards force = ma

- upwards force = ma - mg

Upwards force = (ma - mg) * -1

Then:

T.F = ma

mg - upwards force = ma = m*0 = 0

Mg = Upwards force

m = upwards force/g

Original M - new value for M = delta m = amount the mass must be reduced.

Can anyone enlighten me on where I'm going wrong please, perhaps the upwards force doesn't remain constant, or I'm missing a force in my modelling.

Any help is very much appreciated!!