effects of the forces, properties of sound, how the sound travels.

1. Forces and sound
UNIT 6 NATURAL SCIENCE – YEAR 5

2. FORCES
Forces have
different
effects on
objects.
FORCES
Change
shape
Move
Break
Stop

3. Objects that change shape
 Elastic objects: go back to their initial shape.
 Plastic objects: do not return to their initial shape.

4. Objects that break
 Rigid objects: break when sufficient force acts on them.

5. Forces and movement
 An object will not move unless a force acts upon it.

6. Friction
 It is the force that slows down and stops a
moving object.

7. SOUND
The sound is a vibration.

8. SOUND
 The vibration is transmitted through air like waves.

9. PROPERTIES OF SOUND
Intensity: volume measured in Decibels.
Pitch: speed of vibration.
Timbre: quality of sound that allows us to
identify it.

10. Travel of sound
 The sound travels in a straight line and in all
directions.

11. Echo
 An echo occurs when a sound hits a distant
obstacle. The sound is reflected and returns to our
ears.

12. Reverberation
 Reverberation occurs when a sound is reflected by
a nearby obstacle. The sound returns to our ears
quickly.

13. Noise pollution
 Noise pollution is the level of noise that affects our
hearing, normally with loud and unpleasant sounds.
Video:
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