SCIENCE YEAR 4 CHAPTER 6

What is sound?

• Sound is a source of light

• Sound produce by vibrating objects

• Sound is a energy that produces wind

• Sound is produced by an object that stays in one place

Sound can be reflected

• True
• False

Answer explanation

Sounds can be reflected back as an echo

Which one is true about sound travels through a medium?

• Sound can travel fast in vacuum

• Sound travel faster in water medium compared to air medium

• Sound travel the fastest in air

• Sound travel fastest in solid medium

Answer explanation

Sound travels the fastest in solid medium as the molecules are arranged compact and near to each other

Sound can be reduced by trees

• True
• False

Answer explanation

Trees can absorb the sounds by interfering the sound waves

What is an echo?

• Sound that can be absorbed by the wall

• Sound that can be destroyed

• Sound that travels fastest

• Sound that repeats and caused by the reflected of sound waves from a hard surface back to the listener

Which one of the ways can reduce the sound pollution?

• Place a speaker in the hall

• Open the windows when playing loud musics

• Place sound absorbers in living room

• Use ear protector when working in a loud environment

Loud sounds can be dangerous to ear and damage the hearing

• True
• False

Answer explanation

Hearing loud sounds frequently can affect the eardrums and disturbs the listening process

Which one of the sound applications that use in human and animal life?

• A bat uses echolocation to hunt for preys

• A machine uses electric to produce light

• Medical examiners uses ultrasound to see and check the baby

• Sonar system is used to see the objects under the sea