A cube of wood of density 0.78 g/cm³ is 10 cm on a side.When placed in water,what height of the block will float above the surface? (water density = 1.00 g/cm³) A)7.8 cm B)5.0 cm C)2.2 cm D)6.4 cm

Question

Quizplus · Accepted Answer

When an object floats in water, the weight of the displaced water (called buoyant force) equals the weight of the object. Therefore, we need to find the weight of the cube and the weight of the displaced water to solve for the height that will float above the surface.

Weight of the cube = density x volume = 0.78 g/cm³ x (10 cm)³ = 780 g
Weight of the displaced water = density x volume = 1.00 g/cm³ x (x cm)² x 10 cm = 10x g

Since the weight of the cube equals the weight of the displaced water:

780 g = 10x g 
x = 78 cm / 10 cm = 7.8 cm

Therefore, the cube will float with a height of 7.8 cm above the surface of the water. The correct choice is C.

A Cube of Wood of Density 0