Sienna made a chart listing the steps that describe how a four-stroke heat engine operates. COM
Step
1
Name
intake
2
ignition
Description
piston moves down and fuel-air mixture
enters cylinder
spark plug fires and causes combustion,
leading to gas expansion
piston moves up and temperature of gas
increases
piston moves up, pushing burned gas
through exhaust valve
3
compression
4
exhaust
Which best describes Sienna's error?
o The descriptions for intake and ignition should be switched with one another.
O During compression, temperature does not increase, it decreases.
O Compression happens before ignition, so it should be step 2.
O The piston moves down, not up, during the exhaust step.

1. what is the relationship between wavelength and the penetrating power of an electromagnetic wave? a) the penetrating power has no relationship to the wavelength. b) the penetrating power increases as the wavelength increases. c) the penetrating power decreases as the wavelength increases. d) the penetrating power decreases as the wavelength decreases. 2. as ice melts and turns into water, the speed of sound through the material would most likely do what? justify your answer. a) the speed would not change because the material is always water. b) the speed of sound would increase because the density of water is less than that of ice. c) the speed of sound would increase because energy is added to ice in order to make it melt. d) the speed of sound would decrease because sound travels faster through solids than liquids. 3.which of these waves need a medium to travel through? a) sound b) x-rays c) infrared rays d) visible light