1. T.H. The Professional Development Service for Teachers is funded by the Department of Education and Skills under the National Development Plan The Height Of A Tree

2. PDST Resources for Leaving Certificate Physics 2 The height of a tree  How would you measure the height of this tree?

3. PDST Resources for Leaving Certificate Physics 3 We measured a student’s height.  His height was 1.7 m.  Remember to hold the metre sticks vertically.  Avoid the error of parallax when taking the reading.

4. PDST Resources for Leaving Certificate Physics 4... and the length of his shadow  His shadow turned out to be 3.2 m long.  How are these measurements going to help us to find the height of the tree?  What did we do next?

5. PDST Resources for Leaving Certificate Physics 5 The length of the tree’s shadow  This was 16.3 m in length.  The student’s height was 1.7 m.  His shadow had a length of 3.2 m.  How does this relate to the height of the tree?

6. PDST Resources for Leaving Certificate Physics 6 Look at these similar triangles.

7. PDST Resources for Leaving Certificate Physics 7 Can you work out the tree’s height now?

8. PDST Resources for Leaving Certificate Physics 8 Answer

9. PDST Resources for Leaving Certificate Physics 9 What Next?  Use this method to find the height of a tree or building near you.  Remember: