Kids Riddles

Question: A semi truck weighing exactly 10,000 pounds gets onto a bridge that is 100 miles long. The bridge's weight limit is exactly 10,000 pounds, any more will break the bridge. After going about 80 miles down the bridge a small bird lands on the truck.

What happens?

Question: what did the postman say to the mailbox?

Question: What is big and yellow and comes in the morning to brighten mom's day?

Question: I am an instrument that you can hear, but you can not touch or see me.

What am I?

Question: I go up and I go down,
towards the sky and the ground.
I'm present and past tense too,
Let's go for a ride, me and you.

What am I?