(Assume there is no friction) A bike starts rolling down a hill at 4.3 m/s . After 12 s it reaches the bottom moving at 11.5 m/s. How long was the hill? Express your answer with the correct number of significant digits.

Petroleum contains energy. a. light b. kinetic c. chemical d. mechanical

Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space? the cloud is extremely hot. the cloud is visible primarily because it reflects light from nearby stars. the cloud is cool and lies between you and a hot star. the cloud is cool and very dense, so that you cannot see any objects that lie behind it.

If you visited mount shasta city (elevation 900 m [3000 ft.]) and found the outside air temperature to be 27°c (81°f), what would be the air temperature at the summit of mount shasta (elevation 4200 m [14,000 ft.]) at that moment-assuming that the temperature conditions with altitude change at an average, or normal, lapse rate?