Chapter 9: p.332 2 careers possibilities come up in this chapter Commercial Diving 9 month program at Holland College Reading the intro on p 332 will tell you other one
Density and Volume story...yes, connected to this chapter! Who thought about density? Aluminum vs Gold. And why? (Archimedes 287 212 BC)
Heat ray
Archimedes' screw: a kind of pump to move water https://www.youtube.com/w atch?v=mic3m7apiky
Math...lead to his death... Circle geometry (math) expanded Pythagoras Theorem
The Golden Crown... Density? Mass? Volume...? Archimedes is supposed to have made this discovery when stepping into his bath, causing him to yell 'Eureka!' (which means )
9.1 Forces and Buoyancy Definition: is anything that causes a change in the motion of an object a push or pull Examples of what forces do: (THINK of throwing a ball). 1. 2. 3. 4. A force can start an object to move or stop an object from moving. A force can cause an object to speed up or slow down. A force can change the direction of a moving object. A force can be a bend, twist or squeeze. In science (physics): An arrow is used to symbolize force.
Types of Forces: 1. 2. 3. 4. Buoyancy Magnetic Gravity Friction Draw an example of each..
1. Buoyancy Who is winning in each case?
2. Magnetic
3. Gravity Sir Isaac Newton: (Newton s Laws of Motion)
4. Friction: (wherever there is contact)
Forces A) Balanced Forces: are equal to each other in strength and opposite in direction to each other, there is no motion. Potential energy - stored energy; energy at rest. B) Unbalanced Forces: One force is greater than another, causes a change in speed or direction of an object. Kinetic energy energy in motion
Mass vs. Weight Mass: remains the same no matter where an object is in the universe. The unit for mass is grams (or Kg or mg). Weight: is the measure of the push or pull, of gravity on an object. Weight is measured in units of Newton (N). Ex: The weight of an object on the moon is 1/6 of that on Earth. A 600 N person would weigh 100 N on the moon.
Sketch this in your notes...
Buoyancy The Anti-Gravity Force Buoyancy: is the upward force of an object that is submerged or floating in/on a fluid. In other words buoyancy is the upward push of a substance away from the natural pull of center of the Earth. Buoyancy and Buoyant Force are similar terms Force of Gravity the ball floats Buoyant Force
Archimedes Principle: (law of hydrostatics) The buoyant force acting on an object equals the weight (force of gravity) of the fluid displaced by the object Check out this simulation: https://phet.colorado.edu/sims/density-and-buoyancy/buoyancy_en.html
Many famous paintings about his death noli istum disturbare" https://www.youtube.com/watch?v=0v86 Yk14rf8 Domenico Udine (1815)
3 Scenarios for Buoyancy: (draw and label) Floating, rises up Neutral buoyancy sinking, goes downward
Sinking, rising, floating... see p 337, draw in the forces boat Helium balloon rock KEY: The difference between an object's weight and the buoyant force acting on the object will determine whether the object sinks, rises, or floats.
Archimedes principle: why you sink if you step in water You will sink in the water until your body has displaced the same mass of water as your body mass. You sink because you weigh more than the water you displace.
But if you step into a boat...a larger volume of water is displaced. Boats are often wedge-shaped; the more they are pushed down, the more water they displace. The weight of the displaced water exceeds the combined weight of you and the boat. So, the buoyant force is greater than the force of gravity, and so you and the boat float on the surface.
Design Influences an Object s Ability to Sink or Float Concrete or steel boat vs. a chunk of concrete or a section of steal. A silk/canvas hot air balloon vs. a sheet of canvass. Submarine vs. an iron pole. https://www.youtu be.com/watch?v= AzXGiWBNyqg
Buoyancy and Density: The greater the density of the fluid, the smaller the volume of fluid an object, (like a buoy p339), has to displace in order to float. (draw) Dense fluids provide a greater buoyant force. Salt water (ocean) Fresh water (lake)
Average Density: the total mass of all substances that make up the object divided by the total volume of the object Ex: (draw) steel ship (D= 9.0 g/cm3) large, hollow hull - density of the air in the hulls is very low (approximately 0.0012 g/cm3) hollow hull because the avg. density of the ship is less than that of water.
Lifejackets: are filled with a substance of very low density...like foam. A life jacket lowers a person s average density, allowing the person to float.
Benefits of Average Density: p.340-343 Fish have a specialized organ called a swim bladder. (also called gas bladder)...read more here. This contains and. To sink, it. To rise, it. Swim bladder
Engineers have adapted this principle to control depth in SUBS.