Indirect Observations

10SCIE - Geology

Finn Le Sueur

2024

Pātai

How do we know about the inner layers of Earth? The deepest hole we have ever dug was about \(16km\), and that is nothing compared to the \(6371km\) which is the center of Earth!

Indirect Observations

  • We can look at the magma that erupts from volcanoes that was brought up from inner Earth
  • Earthquakes move through different materials (mediums) at different speed and even change direction a little bit when they go from crust to mantle etc.

Conduct this experiment in your exercise book. Write down the aim etc.

Whakamātau / Experiment

Whāinga / Aim

To demonstrate that unknown substances can be distinguished without observing them directly.

Putanga Iho / Results

Can 1 Can 2
Shake Sound
Shake Feel
Weight
Float
Tap Sound
Roll

Copy this table into your book. Add a couple of rows for your own tests.

Rārangi Mahi / Method

  1. Ask a sibling/caregiver to use two cans of food from the cupboard. These cans should have very different substances in them, e.g. soup and pears.
  2. Perform the following measurements on the cans:
    1. Shake the cans - do they sound different?
    2. Shake the cans - do they feel different when shook?
    3. Weigh the cans
    4. Try to float the cans in water
    5. Tap the cans with a metal implement
    6. Roll them down a slope - which one arrives first?

If you can think of any of your own tests, perform them and record the results!

Now, imagine that you can do these tests on 100 different types of canned food. You would soon be able to determine a pattern and make predictions.

Find a 3rd can of food that is similar to one of your original cans. Does it perform the same as that similar can?

Whakaaroaro / Science Discussion

We can do a similar process with Earth - we measure the speed of sound from Earthquakes and explosions; we measure the viscosity (stickiness) of lava from different volcanoes; we measure the gravity of Earth with satellites; we measure the shape and size of Earth with satellites.

This image shows how gravity varies across Earth’s surface. The colours make it look severe, but dark blue/black is a variation of \(0.00816%\)! A tiny change in the acceleration due to gravity.

Source