Question

Marko and Daniel have worked up a sweat playing fortnite. They both decide to take a quick break and grab a glass of water with some ice in t. Marko's mum does not like how much fortnite the boys play so she decides to play a joke on her son. She fills one cup with fresh water of density p 1000 kg/m3 and another identical cup with salt water of density p 1029 kg/m3, the latter of which is intended for Marko. (a) If the ice cube has a density of p 934 kg/m3 and is floating, what fraction of the ice cube's volume will be submerged in each cups? How could Marko and Daniel tell which cup has salt water and which has fresh water? (b) After working out the correct cup of water (or not) Daniel and Marko proceed to drink the water. Let us model their oesophagi as straight pipes that are l- 50 cm long with the mouth end having a radius of 30 mm and stomach end having a radius of bot 32 mm Tt i) Assume the water enters their oesophagi with a speed of 8.0 m/s. What is the speed at the exit? ii) If the pressure as the fresh water enters the oesophagus is 1.01 x 105 Pa (1 atm), what is the pressure at the exit (modelling the oesophagus as a pipe with rigid walls)? ii) The oesophagus works by a series of muscles that move food/liquid from the mouth into the stomach Why would modelling the oesophagus as a straight pipe be inaccurate for calculating the dynamics of fluids that are traveling through it (Hint: go and eat/drink something upside down)

Answer 1

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