9.1 Floating and sinking

Question 1

Define upthrust

Answer 1

the upward force on an object from the liquid or gas in which it is floating

Question 2

Define balanced forces

Answer 2

when the resultant force is zero.

Question 3

define unbalanced forces

Answer 3

when there is a resultant force.

Question 4

define resultant force

Answer 4

the single total force acting on an object when all the forces acting on it are added up.

Question 5

density formula

Answer 5

density = mass/volume

Question 6

What are the conditions for floating and sinking in terms of density

Answer 6

Solids and liquids that are less dense than water float in water. Gases that are denser than air will sink and gases that are less dense than air rise.

Question 7

Explain why hot air balloons rise in air

Answer 7

As the temperature of air increases, volume increases, hence the density of air decreases. So, the hot air balloon becomes lighter and rises.

Question 8

Ice floats in water. What does this tell you about the spacing of ice particles?

Answer 8

The particles in the ice are more far apart than the particles in water.