Answer: 0.002 newtons
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Work Shown:
I'm assuming you meant to write "at 20 m/s^2" at the end. If so, then,
0.10 grams = 0.10/1000 = 0.0001 kg
m = 0.0001 kg = mass
a = 20 m/s^2 = acceleration
F = ma .... newton's second law
F = 0.0001*20
F = 0.002
The force required is 0.002 newtons