Aboy yells in a narrow valley. the sound reflects off of a boulder that is 80 m away. how long will it take to hear the echo if
the speed of a sound wave is 320 m/s?
(speed = distance
time
0 25 seconds
0.50 seconds
2.0 seconds
4. biseconds
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1: 33 pm
8/29/2019
hewlett-pac

Sarah is sitting at the top of the slide in the schools playground. which will increase sarah’s kinetic energy a- an additional child is added to the top of the slide. b- sarah is pushed and moves down the slide. c- sarah climbs down the ladder and off the slide. d- the ladder is moved to the other side of the yard.

Read the following scenario to answer the following question. in some zoos, rare crosses between a male lion and a female tiger have produced hybrid offspring called "ligers." male ligers are sterile but some female ligers are fertile. in the wild, lion and tiger ranges do not naturally overlap, making such a cross unlikely. furthermore, the solitary behavior of tigers and the social organizations of lions create behavioral differences. applying the biological species concept, the sterility of ligers reveals that a. lions are probably a subspecies of tigers b. tigers and lions are the same species c. a new species called "ligers" is forming d. tigers and lions are separate species

Ascientific idea becomes valid when it is what?