Forensic Friday #8 – Density Matters

A couple of days ago, Nefarious had lined up Zaltu’s Batman toys.

“Originally, I had them lined up in size. But then this one was smaller but heavier. So I thought to go with something different and do them by weight instead.”

Great opportunity for a lesson in density. Not only will the spawnlings understand a basic scientific concept, but it will help them understanding other minions in the world – like politicians.

Today’s Forensic Friday is a man down; Sinister abandoned us for a day of Minecraft looting with a friend. So let’s make it 6yo (first grade) friendly.

What is Density?

Density is a measurement of how solid something is. If you have two objects of the same size, the more dense object will weigh more than the less dense object. This is because of two things:

  1. The mass of the atoms that make up the object;
  2. The amount of space the object takes up. If the atoms are packed in tightly, it will be denser. I used the example of a ‘dense forest’ and whether you could move easily between the trees. Another example you could use is whether that particular minion has enough space in their brain for ‘free thought’ to flow through – or if they are ‘dense’. We’ve had a few examples of this recently, but I didn’t want to distract Nefarious too much.

The next step to take is to look at the relationship between density and buoyancy. We’re going to come back to this when Sinister comes home because he is really into Marine Biology and this is a core concept to remember when diving. Basically, a less dense substance will float on a more dense substance. A good experiment is the Layer Effect:

Ingredients / Photo by Evil Genius Mum

Ingredients / Photo by Evil Genius Mum

What You Will Need:

  • Oil
  • Water
  • Honey or Golden Syrup (Honey is better to see through, but we were out of honey today)
  • Cork or Styrofoam
  • Grape or Blueberry or Strawberry or something similar
  • Small coin
  • Clear bottle

What You Do:

  1. Fill your bottle one third with honey;
  2. Pour the next third full with oil
  3. Fill the remaining third with water. Allow the liquids to settle before the next step.

    Pouring the Liquids / Photo by Evil Genius Mum

    Pouring the Liquids / Photo by Evil Genius Mum

  4. Take a minute to explain to your spawnlings about the separation of liquids here. Honey/Golden Syrup is really dense, so it will sink to the bottom. Water is not as dense as the syrup but it is definitely more so than the oil. Fortunately, oil and water don’t mix, so they will separate with the oil resting lightly on top.
  5. Let’s just stop for a moment and do a bit of hypothesising. Science ain’t science without a hypothesis, a method, and a written report afterwards. Otherwise, it’s just messing around with stuff. Ask your spawnlings what they think will happen to the next three items: the coin; the fruit; the styrofoam or cork.
  6. Now, drop the coin in the bottle. The coin will drop all the way to the bottom, even through the honey. Thank you, my dense little 10c and 5c pieces.
  7. Next drop the grape or blueberry in (blueberry for us – Zaltu was pigging out on the grapes while Nefarious and I set up the experiment). This one should rest somewhere around the middle.
  8. Finally, the cork or styrofoam. Being REALLY LIGHT, it should rest easily on the top.
Liquid Density / Photo by Evil Genius Mum

Liquid Density / Photo by Evil Genius Mum

And there you go folks! A lovely little lesson in density. When Sinister and EG Dad come home, we might take it the next step and look at buoyancy from a scuba diving point of view. Since I’m asthmatic, I have never been diving so wouldn’t know WTH I’d be talking about. 😛

My Budding Scientists / Photo by Evil Genius Mum

My Budding Scientists / Photo by Evil Genius Mum

One thought on “Forensic Friday #8 – Density Matters

  1. Pingback: EG Parent Award #60 – Physics | Evil Genius Mum

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