Density, Buoyant Force,and Archimedes’ Principle
How many pennies can your boat hold?How many pennies can your boat hold?
What makes something float or sink?What makes something float or sink?
• DENSITY!DENSITY!• Let’s review:D = m / VD = m / V
Cruise Ships – 50,000 tons!Cruise Ships 50,000 tons!
But what’s really making the less d h fldense things float?
• When we put a boat in waterWhen we put a boat in water, what do you observe?
Water is “displaced”
But how much water is displaced?But how much water is displaced?
• http://wwwyoutube com/watch?v=eQsmq3Hhttp://www.youtube.com/watch?v=eQsmq3Hu9HA
Archimedes’ PrincipleArchimedes Principle
The buoyant force on a fl i b dfloating or submerged
object is equal to the weightobject is equal to the weight of the displaced fluidof the displaced fluid.
Question:Question:• A rectangular barge 300cm long and 200cm wide floats at the edge of a fresh water lake.
• A horse jumps into the barge, and the barge j p g gsinks 12cm. How much does the horse weigh?
720kg• 720kg
Penny‐boat challengeTake 2!Take 2!
Challenge question…Challenge question…
• I’m sitting in a boat with a really big boulderI m sitting in a boat with a really big boulder. If I throw the boulder overboard, the water level will:level will:
A. go upB hB. stay the sameC. go down
Which bottle + weight system will float c bott e e g t syste oatHIGHER in the water?
Dipping a finger in a glass of h ill h hwater, what will happen to the
scale reading?scale reading?
https://mrhorn.com/moodlehttps://mrhorn.com/moodle
2011 ATP P22011‐ATP‐P2