To make your formula neater:

Acceleration is equal to
,
so when you multiply it by time, you will get a velocity. In fact, you would get the change in velocity, as a*t signifies the acceleration of the object over the time, aka the change in velocity.
The initial velocity plus the change in velocity will equal the final velocity, irregardless if the change in velocity is positive or negative.
Therefore,

It's acceleration is 9.8 m/s^2 in the negative y direction, from the time it leaves the hand until it hits the floor.
A closed circle means the number is included and an open circle means its not.
Work is done when a force acts on an object AND the object moves in the direction of the force.
-- <em>Pulling a trailer up a hill. YES. </em> The trailer is moving in the direction of the pulling force.
-- Carrying a box down a corridor. No. The box is not moving in the direction of gravity (down) OR in the direction of your arm (down the corridor).
-- Suspending a heavy weight with a strong chain, No. There's a force (gravity) acting on the weight, but the weight is not moving at all.
-- Pushing against a locked door. No. There's a force (your muscles) acting on the door, but he door is not moving at all.
The correct answer (sample response) is:
The image seems to be behind the mirror, but nothing is really there.
Include the following in your response:
The image appears to be behind the mirror.
If someone looks behind the mirror, there is no image there.
