Logic Riddles

Question: You are in a car with some helium balloons and hit the gas. While you accelerate, which way does the balloon move?

Question: If a mountain climber climbed up a mountain one day from midnight to midnight the next day and does the same thing the following day when coming down the mountain, would there be a time at which he was at the same position on the mountain both day?

Question: When is a door not a door?

Question: An apple tree has apples on it. A storm comes through and there is no longer apples on the tree. But there isn't apples on the ground either.

How can this be so?

Question: A man built his house above a river between two trees. He attaches his house to the middle of the two tree's trunks. He does this because the river rises by 2 inches each years, but the trees grow 1 inch each year. If his house is 4 inches above the river how long will it take for water to hit his house?