Sound
What must an object do to produce sound?
Vibrate.
What is it called when light bounces off a surface?
Reflection.
Which type of mirror curves inward and can magnify nearby objects?
A CONCAVE mirror
What two characteristics define matter?
It has MASS and TAKES UP SPACE
What is the change from solid to liquid called?
Melting
Why can sound travel through air but not empty space?
Sound needs matter to carry its vibrations.
What is it called when light bends as it passes between materials?
Refraction
Which mirror provides a wider view while making objects appear smaller?
A CONVEX mirror
Gold contains only one type of atom. Is it an element, compound, or mixture?
ELEMENT
A puddle disappears without being boiled. What process caused this? (Change from liquid to gas)
Evaporation
If a sound’s frequency increases, what happens to its pitch?
Its pitch becomes higher.
Why does a straw look bent where it enters water?
Light changes speed and refracts as it travels between water and air.
What does a convex lens do to parallel light rays?
Brings them together, or converges them.
Why is pure water a compound?
It contains two elements- HYDROGEN AND OXYGEN (bonded together)
What is the change from liquid to solid called, AND does it require ADDING or REMOVING thermal energy?
Freezing; thermal energy is REMOVED
Which wave property increases when a sound becomes louder?
Amplitude.
Can light travel through empty space?
Yes. Light does not need matter to travel.
What does a concave lens do to parallel light rays?
Spreads them apart, or diverges them.
Salt water is evenly mixed, while trail mix has visibly different parts. Which is homogeneous, and which is heterogeneous?
Salt water is homogeneous. Trail mix is heterogeneous.
Describe the following two changes as either a PHYSICAL CHANGE or CHEMICAL CHANGE- 1) an iron nail rusts 2) a piece of paper is cut up into small pieces
1 = chemical 2 = physical
How does sonar help a boat locate objects underwater?
It sends sound waves and detects the echoes reflected from objects.
Light strikes a mirror at an angle of 30°. What is its angle of reflection?
30° angle. The incoming and reflected angles are equal.
Do lenses mainly work by reflecting light or refracting light?
REFRACTING light (bending it)
Match salt water, milk, and muddy water to solution, colloid, and suspension.
Salt water=solution; milk=colloid; muddy water=suspension
What is the most important difference between a physical change and a chemical change?
A chemical change forms new substances; a physical change does not. A physical change keeps the substance the same thing at the end.