(Question)
Answer the following question given this paragraph: Friction is the force that resists motion. In most beginning physics classes, friction is ignored. Concepts can be understood and calculations made assuming friction to be nonexistent. Whenever physics intersects with the real world, however, friction must be taken into account. Friction exists between two touching surfaces because even the smoothest looking surface is quite rough on a microscopic scale. Q: What type of force exists between two touching surfaces? Choices: - opposing - centrifugal - tension - friction A:
(Answer)
friction

(Question)
Answer the following question given this paragraph: Wave speed is related to both wavelength and wave frequency. Wavelength is the distance between two corresponding points on adjacent waves. Wave frequency is the number of waves that pass a fixed point in a given amount of time. This equation shows how the three factors are related:. Q: In physics, the number of waves that pass a fixed point in a given amount time is referred to as what ? Choices: - combination frequency - wave count - creation frequency - wave frequency A:
(Answer)
wave frequency

(Question)
Answer the following question given this paragraph: Humans have caused many extinctions by introducing species to new places. For example, many of New Zealand's birds have adapted to nesting on the ground. This was possible because there were no land mammals in New Zealand. Then Europeans arrived and brought cats, foxes, and other predators with them. Several of New Zealand's ground nesting birds, such as this flightless kiwi, are now extinct or threatened because of these predators. Q: What can ultimately result when species are introduced to a new place and prey on other species? Choices: - depletion - over population - elimination - extinction A:
(Answer)
extinction