You are going to toss a rock straight up into the air by placing it on the palm of your hand (you're not gripping it), then pushing your hand up very rapidly. You may want to toss an object into the air this way to help you think about the situation. Draw the free body diagram of the rock:

As you hold the rock at rest on your palm, before moving your hand.

As your hand is moving up but before the rock leaves your hand

One-tenth of a second after the rock leaves your hand.

After the rock has reached its highest point and is now falling straight