| Your Results | Global Average | |
|---|---|---|
| Questions | 5 | 5 |
| Correct | 0 | 3.57 |
| Score | 0% | 71% |
The pitch of the siren of an approaching ambulance changes as it approaches you. This is an example of which of the following?
sound radiation |
|
reflection |
|
refraction |
|
Doppler effect |
The Doppler effect occurs when the source or listener (or both) of sound waves is moving. If they're moving closer together, the listener perceives the sound with a higher pitch and, when they're moving apart, the listener perceives the sound with a lower pitch.
Which of the following states of matter exists at the lowest temperature?
solid |
|
none of these |
|
gas |
|
liquid |
Solids exist at a lower temperature than liquids which exist at a lower temperature than gases.
The formula for acceleration is which of the following?
\(\vec{a} = { m \over F }\) |
|
\(\vec{a} = { \vec{F} \over m }\) |
|
\(\vec{a} = \vec{F} m\) |
|
\(\vec{a} = { m \over \vec{F} }\) |
Newton's second law of motion leads to the formula for acceleration which is a measure of the rate of change of velocity per unit time and, if you solve for positive acceleration, reveals how much net force is needed to overcome an object's mass. The formula for acceleration is \(\vec{a} = { \vec{F} \over m }\) or, solving for force, \(\vec{F} = m\vec{a}\).
Which of the following is not one of the outer planets?
Neptune |
|
Venus |
|
Jupiter |
|
Uranus |
In contrast to the solid terrestrial planets, the outer planets (Jupiter, Saturn, Uranus, and Neptune) consist of hydrogen and helium gas and water.
Which of blood component fights infection?
plasma |
|
white blood cells |
|
red blood cells |
|
platelets |
Blood is created in bone marrow and is made up of cells suspended in liquid plasma. Red blood cells carry oxygen, white blood cells fight infection, and platelets are cell fragments that allow blood to clot.