Ketchup Packet Cartesian Diver
Supplies:
Ketchup packet that barely floats
water
plastic bottle with lid
Build
Build: Place ketchup packets in a cup of water. Find one that floats, but stays mostly submerged.
Place the ketchup packet in the plastic bottle.
Fill with water until entirely full.
Screw the cap on tightly.
Your build is done
Interaction
Interaction: F=Facilitator P=Participant
F: Would you try squeezing the bottle tightly.
P: OK
F: What happened when you squeezed the bottle?
P: The ketchup packet sinks.
F: Why do you think that is?
P: Pressure/density force/ magic/magnets and many other crazy answers.
F: What makes something sink or float
P:??? Pressure??? How heavy it is
F: Close. An Iceberg is very heavy but it floats while a dime is light but it sinks? We want to talk about density mass per volume. (Beneficial to have two objects of same mass but different density one that floats and one that sinks.) Which will float and which will sink?
P:Points correctly
F: Correct it has the same mass but in a smaller volume so it has a higher density.
F: what could make the ketchup packet change density when you squeeze it?
P: We're crushing the ketchup? F: In the ketchup packet there is a tiny bit of air.When you squeeze the bottle the air get compressed into a smaller space so the density increases. Then the density of the packet is higher than the density of the water and it sinks. When we let go the air expands and the density of the packet is lower than the density of the water and the packet floats. Link to more comprehensive description