FLOATING AND DENSITY WHAT WE KNOW Objects sink when their mass is greater than the mass of the fluid they displace. But what happens if the properties of the fluid change? For example floating the same object in canola oil? BUOYANCY AND DENSITY Different fluids can have different densities. Because density can affect the mass, an object that may float in one fluid may not float in another BUOYANCY AND DENSITY Have you ever swam in an ocean or a mineral lake? Did you notice that it was easier to float in this water Because the water is more dense than freshwater it is heavier. This means that there is more buoyant force BUOYANCY AND DENSITY Warm water is less dense than cold water. Because of this ships designed to carry heavy loads in cold water can sink lower into the water when traveling in warm water. TYPES OF FORCES CONTACT FORCE A contact force is one where a push or pull is exerted when two things are touching one another NON-CONTACT FORCE A non-contact force is one where a push or pull is exerted when two things are not actually touching EXAMPLES Buoyant force is a contact force because it is caused by the particles pushing against one another Gravitational force is a non-contact force because it is caused by the attraction between earth an an object. This force exists even if the object is not touching the ground TIME TO THINK What kind of force is magnetism? Non-contact What kind of force is made by you when pulling on a rope? Contact