You place a block of wood into a beaker of water and it floats. What can you say about the buoyant force on the block?

1 Answer
Apr 26, 2016

The buoyant force is stronger than the gravity force (the block's weight). Consequently, the block's density is smaller than water's density.

Explanation:

Archimedes principle affirms that a body submerged in a fluid (for example a liquid, or more precisely, water) experiences an upward force equal to the weight of fluid (liquid, water) displaced.

Mathematically,

buoyant force = F_b = V_b *d_w*g
V_b = body volume
d_w = water density
g = gravity acceleration

while the weight W= V_b*d_b*g

d_b= body density

As the body floats => F_b > W => d_w>d_b