21. When getting ready for a picnic, you pack some cold food in a foam-type container. Why will the food remain cold in the foam-type container longer than it would in a paper sack?
a. The container material is a good conductor of thermal energy.
b. The container material is a good insulator.
c. The container material causes the density of the cold air inside the container to decrease, making it more difficult to lose heat.
d. The air pockets in the container material absorb heat.
22. Which of the following descriptions depicts an example of the first law of thermodynamics?
a. Thermal energy from an ice cube moves into a hot beverage.
b. The decrease in thermal energy of a hot object must be greater than the increase in thermal energy of a nearby cool object.
c. Heat energy cannot be transferred across the boundary of a system unless work is done by the system.
d. The cylinder of an air pump gets warmer as the piston moves inside it.
23. Which of the following is an example of a system that has experienced an increase in entropy?
a. Liquid water becomes an ice cube.
b. Liquid water condenses on the outside of a glass.
c. The liquid coolant inside a refrigerator changes to a gas.
d. The compressor component of a refrigerator cools the circulating gas.
24. Which of the following which types of waves can travel without a medium?
a. sound
b. radio
c. mechanical
d. transverse
25. The type of waves that pass through a coiled metal spring are called
a. transverse waves.
b. electromagnetic waves.
c. compressional waves.
d. seismic waves.
26. The average speed of sound in water is approximately 1,500 m/s. If the noise from a boat takes 5.0 seconds to reach an underwater detector, how far away is the boat? (d/s = t)
a. 0.0033 m
b. 300 m
c. 1,505 m
d. 7,500 m
27. If two radio stations have broadcast waves of 3.0 meters and 2.0 meters respectively, what else can you say about the radio waves?
a. The one with the shorter wavelength will have a smaller frequency.
b. The one with the shorter wavelength will have a higher frequency.
c. The one with the longer wavelength will have a longer frequency.
d. Since they are both radio waves, they will have the same frequency.
28. If you hear a musical sound from an instrument that is vibrating the air at 200.0 Hz and traveling at 340 m/s, what is the wavelength of that music?
a. 1.7 m
b. 0.59 m
c. 68,000 m
d. 0.0050 m
29. Seeing an image in a mirror is a function of what behavior of light?
a. refraction
b. diffraction
c. reflection
d. resonance
30. When a wave bends as it enters a new material, it is called
a. interference.
b. diffraction.
c. reflection.
d. refraction.Home work help best answer?21. b; 22. d; 23. c; 24. b; 25. b; 26 b; 27. b; 28. ?; 29. c; 30. d
I'm not positive about some of them. It would help if I had studied this recently. Most of them you can do with common sense.Home work help best answer?dont you have a book
or google.
