During a thunderstorm, the temprature is 18C. If you see a lightning flash and hear the thunder 1.5 seconds afterwards, how far away is the thunder really?

Which type of wave can travel without a medium

What is the most useful equation for electric power?

The star betelgeuse is about 600 light-years away. if it explodes tonight, a. we'll know because debris from the explosion will rain down on us from space.b. we'll know it immediately because it will be brighter than the full moon in the sky.c. we won't know about it until 600 years from now.d. none of the above.