What goes up but never comes down?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

Can you solve the below geography rebus by decoding the below rebus ?

How many triangles are there in the picture below?

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

Which English verb becomes past tense just by rearranging the letters?

In a concert, Christina is performing a dance show with her group.
At 10:00, she and her crew were dancing in an absolutely straight line. At that time Christina was standing in 4th position from both the front and back end of the row.

What was the size of her crew?

A worker is to perform work for you for seven straight days. In return for his work, you will pay him 1/7th of a bar of gold per day. The worker requires a daily payment of 1/7th of the bar of gold. What and where are the fewest number of cuts to the bar of gold that will allow you to pay him 1/7th each day?

What has hands, but can’t clap?