Density

A student places the following objects in water to see if they will float. Which set of items is less dense than water?

• Plastic paper clip, penny, and cork

• Toothpick, metal spoon, and plastic paper clip

• Metal spoon, vegetable oil, and penny

• Toothpick, cork, and vegetable oil

A student poured an equal amount of water and cooking oil into a jar. The student placed a lid on the jar and shook the mixture for five seconds and then let the jar sit for ten minutes. The results of this investigation are shown. Which conclusion best compares a property of cooking oil and water shown in this investigation?

• Cooking oil is less dense than water

• Water is less dense than cooking oil

• Water dissolves in cooking oil

• Cooking oil dissolves in water

A group of students is given four small cubes of the same size and instructed to place them in a beaker of water. One cube floats to the surface of the water. Two of the cubes float in the middle of the beaker under the surface of the water. The last cube sinks to the bottom of the beaker.

Which conclusion is best supported by what the students observed?

• Two of the four cubes are soluble in water.

• All four cubes have different masses.

• Each cube is made of a different type of solid material.

• One of the cubes is more dense than the other three.

The table lists some physical properties of two objects.

Based on their properties, which of the objects is most likely a metal?

• Object 1, because it is a solid that is less dense than water

• Object 2, because all metals float in water

• Object 2, because metals conduct thermal energy and electricity

• Object 1, because it can be used to provide insulation for thermal energy

Which two objects are most likely less dense than water?

• Wood block and metal paper clip

• Plastic ball and glass marble

• Metal paper clip and glass marble

• Wood block and plastic ball

Objects that blow into a swimming pool or that are dropped into the pool by swimmers need to be removed. These objects include foam cups, keys and coins. Which of the following explains a useful method of removing some of these objects?

• The keys and coins are less dense than water, so they can be easily picked up off the bottom of the pool by divers.

• The foam cups have the same density as water, so they can be crumbled up for the removal by the pool filter.

• The foam cups are less dense than water, so they can be removed from the surface with a pool cleaning net.

• The keys and coins have the same density as water, so they can be washed away when the pool is drained.

Why would the student shake the salad dressing well before using it?

• Vinegar and oil have different densities.

• Vinegar and oil easily form a solution.

• Vinegar and oil both contain water.

• Vinegar and oil are both liquids.

If an object is less dense than water it will...

• Sink

• Float

If an object is denser than water it will...

• Float

• Sink

Mass and density are the same things

• True

• False