CK-12 Physical Science - For Middle School

http://www.ck12.org Chapter 15. Fluid Forces

FIGURE 15.14

The substances pictured here float in a

fluid because they are less dense than the

fluid.

or floats. Less dense objects and fluids float in fluids with greater density.

• The buoyant force acting on an object in a fluid equals the weight of the fluid displaced by the object. This
  is known as Archimedes’ law (or Archimedes’ Principle). It explains why some objects float in fluids even
  though they are very heavy.

Lesson Review Questions

Recall

1. What is buoyancy?


2. Describe how weight and buoyant force determine whether an object sinks or floats.


3. How is density related to buoyancy?