funny, actually, i'm a hydraulic, and pneumatic cylinder, pump, and line system mechanic, and the answer is pressure.... pressure builds up from the hydraulic pump, and then transfers through hoses to extend, and contract the cylinders by filling them with hydraulic fluid, and vice versa for contracting them.
hope this helps!
<span>The reason that the balloon will stick to the wall is because the negative charges in the balloon will make the electrons in the wall move to the other side of their atoms and this leaves the surface of the wall positively charged.</span>
Hmm doesnt soujd familiar
Is there any other information given? I don't think you can solve this without a time