How Life Jackets Work

The video explains how life vests work by using Archimedes' principle, which states that an object submerged in water displaces water equal to its mass. The buoyant force, which is the upward push from the water, helps objects float. The video compares a marble and a ping pong ball to illustrate density and buoyancy. It also discusses human buoyancy and how life jackets provide additional lift to keep a person afloat. Life jackets use materials like plastic foams with closed cells to trap air and enhance buoyancy.

What principle explains the upward force experienced by objects submerged in water?

• Bernoulli's Principle

• Pascal's Law

• Archimedes' Principle

• Newton's Third Law

Why does a marble sink in water while a ping pong ball floats?

• The marble is less dense than the water.

• The marble is denser than the water.

• The ping pong ball is heavier than the marble.

• The ping pong ball is denser than the water.

What is the term for the force that keeps objects afloat in water?

• Gravitational force

• Centripetal force

• Buoyant force

• Magnetic force

How much additional buoyancy does an average person need to float?

• 3 to 5 pounds

• 7 to 12 pounds

• 15 to 20 pounds

• 20 to 25 pounds

What material is commonly used in life jackets to provide buoyancy?

• Rubber sheets

• Wooden blocks

• Plastic foams

• Metal foams