the answer to the mystery of event 3-R. Jumping Juice is again related to expansion and contraction of air. the air inside the bottle expands when hot water is poured over the flask. thus, the air expand and forces the colored water up the glass tube. however, when cool water is used, the air inside contracts and the colored water in the tube drops quickly.
in event 3-S. the sagging solid the metal strip does not reallry sag. ti just bends in response to expansion and contraction. the event can only be done with a special bimetal strip - a sandwich of two metal joined together to look like a single strip.
the strip bends when heated because the metals have different ratesof expansion. one of the metals expands much more than the other. to allow for the different rates of expansion, the strip must bend.