A person of mass 75g stands on the floor of a lift. Calculate the force of the floor of the lift exerts on the person when the lift accelerates downwards at 2m/s^2. I'm just wondering if the acceleration of the acceleration is positive or negative in this case?

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anonymous · Answer

I was pretty sure it was negative but in the answer on my notes it says positive.

anonymous · Answer

In my opinion the sign of the acceleration is just related to your assumption of the positive or negative direction at the beginning when you start to solve the problem.So don't highly care about it and just take the downward acceleration positive which is in the direction of Acceleration of gravity of Earth. It seems so for your lecture notes.|dw:1326634334983:dw|