DensityIB MYP Physics: Subtopic test

1. 1
   A jeweller in Jaipur is testing a solid rectangular metal block. The block has a mass of 324 g and measures 4.0 cm by 5.0 cm by 6.0 cm.

   (a)

   What is the volume of the block?

   [1 mark]

   • A15 cm³
   • B30 cm³
   • C60 cm³
   • D120 cm³

   (b)

   What is the density of the block?

   [1 mark]

   • A0.37 g/cm³
   • B2.7 g/cm³
   • C27 g/cm³
   • D38 880 g/cm³

   (c)

   The density of the block is 2.7 g/cm³. Convert this to kg/m³.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A ship designer in Busan tests three materials in fresh water, which has a density of 1.0 g/cm³. The density of the wood is 0.60 g/cm³, the density of the plastic is 1.2 g/cm³ and the density of the steel is 7.8 g/cm³.

   (a)

   Which materials will float in fresh water?

   [1 mark]

   • AThe wood only
   • BThe plastic only
   • CThe wood and the plastic
   • DThe steel only

   (b)

   A steel ship floats, even though steel is denser than water. Why?

   [1 mark]

   • ASteel becomes less dense when it touches water
   • BSalt in sea water makes steel lighter
   • CThe average density of the ship, including the air inside the hull, is less than that of water
   • DThe mass of the steel decreases at sea

   (c)

   Calculate the mass of 50 cm³ of the wood.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student in Accra wants to find the density of a small irregular stone. She has a balance, a displacement can filled to the spout with water, a measuring cylinder and some string. She finds that the stone has a mass of 84 g and that the water displaced by the stone measures 30 cm³.

   (a)

   Outline how the student could have obtained the mass and the volume of the stone.

   [3 marks]

   (b)

   Calculate the density of the stone. State whether the stone would float or sink in water, and give a reason.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A town in northern Finland has a large freshwater lake. In winter the lake freezes from the top: ice, with a density of 0.92 g/cm³, floats on liquid water, which has a density of 1.00 g/cm³, and fish live in the liquid water beneath. The town's trucks use the frozen lake as a road to reach a remote island community.

   (a)

   Describe how the density of a substance changes between its solid, liquid and gas states, and use density to explain why ice floats on water.

   [6 marks]

   (b)

   Evaluate the use of the frozen lake as a road for the town's trucks.

   [6 marks]

   Total for question 4: 12 marks

End of questions