In the top row labeled Before Collision, the left train car approaches the right car with a grey arrow pointing to the left car car. The left car has below it m subscript 1 = 600 kilograms v subscript 1 = 4 meters per second. The right car has below it m subscript 2 = 400 kilograms v subscript 2 = 0 meters per second. In the bottom row labeled After Collision, two train cars move away linked together with a grey arrow pointing toward the right of the car on the right. Consider a system to be one train car moving toward another train car at rest. When the train cars collide, the two cars stick together.

What is the total momentum of the system after the collision?

800 kg • m/s
1,600 kg • m/s
2,400 kg • m/s
4,000 kg • m/s

19. explain why a magnet from your refrigerator could not be used to lift something as heavy as a car. (chapter 7 – pages 202-203) 20. can a magnet ever have a single pole? explain your answer. (chapter 7 – page 208) 21. what happens to the wavelength of a wave if the frequency is increased? (chapter 9 – pages 280-281) 22. an ocean wave has a wavelength of 10 m and a frequency of 4.0 hz. what is the velocity of the wave? show the appropriate equation from your book and show your work with units. (chapter 9 – page 282) 23. as you sit outside, the sound of a siren becomes lower in pitch. is the emergency vehicle moving away from or towards you? explain how you know. (chapter 10 – page 315-316) 24. why are two astronauts in space unable to hear one another? (chapter 10 – page 307) 25. explain in at least 3 sentences how electromagnetic waves form. (chapter 11 – page 338-339) 26. using the chart on page 345 in your textbook, what are the three types of electromagnetic wave with wavelengths shorter than those of visible light. give an example of each. (chapter 11 – pages 345-351) 27. explain why a leaf usually appears to be green, but a rose typically appears red. (chapter 12 – page 373) 28. what is the difference in light that is refracted compared to light that is reflected? think in terms of speed of light as well as what happens to light waves when they interact with a medium. (chapter 12 – pages 369-370) 29. how are concave and convex lenses different? (chapter 13 – page 408-410) 30. what type of mirror is used in rearview mirrors in cars? why is it important that these mirrors have the warning, “objects in mirror are closer than they appear.”? (chapter 13 – page 405)

If frequency goes down, what happens to wavelength? does it get shorter or longer?

Which form of pure carbon is so hard that it can be used in cutting tools?