Gravitational force on the way up and down?

Always I know the gravitational force of the things going down is NEGATIVE(-9.81m/s^2) and going up is POSITIVE. But, I read question example in a book about flipping coin up; from A to B the way up and B to C the way back down. I’m confused because they used gravitational force on the way up is NEGATIVE. Can... show more Always I know the gravitational force of the things going down is NEGATIVE(-9.81m/s^2) and going up is POSITIVE.

But, I read question example in a book about flipping coin up; from A to B the way up and B to C the way back down. I’m confused because they used gravitational force on the way up is NEGATIVE.

Can someone shed some light??

And, this is applying to the velocity as well??
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