What has no weight, can be seen by the naked eye and if you put it in a barrel, it makes the barrel lighter?

Monday I bring you tears, Tuesday I fuel your fears. Friday you love me more, Because I open freedom's door. Guess what I am?

I hold the whole universe in a pane of clear glass, Stealing your moments as your lifetime walks past. What am I ?

I may be intangible, I may be physical, and at this point, you may be quizzical; But many things are sounds as well as objects. Onomatopoetic, right? You get my logic. Ariana, she made a song about seven But as soon as your effort is turned up to eleven, The logo’s just six? What’s that about? But I mean, these athletes don’t have as much clout.

I stand in the forest, though I have no leaves of my own, I ride in the back of your car, wherever you roam. I am the long nose of a beast who is massive and gray, And you pack me with clothes when you're going away.