Bouyancy

An object floats when density of the object is...

• less than the density of the fluid it is submerged in

• more than the density of the fluid it is submerged in

• Gravitational Force

Answer explanation

Buoyant force needs to equal the weight of the object (gravity) for it to float. If it is too dense (too heavy) it will overcome the buoyant force and sink to the bottom.

Archimedes Principle means...

• force exerted on an object

• total forces that cancel each other out

• the weight of the object equals the amount of fluid displaced

• the attraction between the earth and an object

Answer explanation

Archimedes wondered why he would sink if he stepped into a bathtub, but he would float if he stepped into a boat on the water. He came to the conclusion that the buoyant force acting on an object equals the weight of gravitational force of the fluid displaced by the object. 

Animals in nature have developed several mechanisms to control their density (select all that apply)

• Adjusting amount of air or water in their body

• they only swim at a certain depth

• adjusting the shape or fat content of their body

• muscle development

Answer explanation

The fish uses its swim bladder to control the depth it swims at. By increasing the amount of air in its swim bladder, the fish’s volume increases, therefore more water is displaced.

It can also "squish" its bladder to accomplish this.

Constructed devices control their buoyancy by adjusting (select all that apply)

• Volume of the chamber

• Density surrounding the fluid

• Shape of the device

• Weight of the device

Cargo ships have developed this to determine how heavily the ship can be loaded to be safe under different water conditions

• Cargo Ships

• Bathyscaphe

• Density Regulators

• Plimsoll Line

Answer explanation

 The plimsoul line shows how heavily a ship can be loaded to be safe under different water conditions. The marks on the left of the line indicate where the water line should be in freshwater and the marks on the right indicate where it should be in salt water. This is a safety measure to deal with differing densities of salt and freshwater.

The bathyscaphe is...

• A type of fish that lives in deep in the ocean

• Cargo Ship

• Ship that explored Mariana Trench

• Chart that divers use to make sure they don't explode after a deep dive

Answer explanation

The only manned vessel to reach the bottom of the Mariana Trench was the bathyscaph Trieste, invented by Swiss scientist Auguste Picard. It carried Don Walsh and Auguste’s son, Jacques Picard to a depth of 10 911 m. The name comes from the Greek words bathos for “deep” and scaphos for “ship” ​​

Review: A force diagram is...

• contact force

• a visual representation of the forces acting on an object

• total force acting on an object

• supportive force

Answer explanation

Force diagram is a visual representation of the forces acting on an object.

Review: Net Force is...

• contact force

• a visual representation of the forces acting on an object

• total force acting on an object

• supportive force

Answer explanation

The total force acting on the object. When forces are acting in the same direction you ADD them. When forces are acting in opposite directions you SUBTRACT them.

Review: Normal Force is...

• contact force

• a visual representation of the forces acting on an object

• total force acting on an object

• supportive force

Answer explanation

Any time an object is in contact with the ground it has normal force. If there was no normal force everything would be floating.

Review: Balanced Force is...

• net force acting on an object IS zero

• net force acting on an object is NOT zero

• visual representation of the forces acting on an object

• supportive force

Answer explanation

Equal amount of force acting in opposite directions. This creates a zero net force (because the subtracted forces equal zero) and means the object is not moving.