Alayer of material that block the transfer of heat between the air inside and outside a building is called
a. an active solar system.
b. a solar cell.
c. a heat exchanger.
d. insulation.

15. give an example for some particles or waves that are moving faster than light in everyday life 16. what is a laser? 17. what is an oscilloscope? 18. what does it means practically that nothing is faster than light in vacuum? 19. what is vacuum?

In all trials, the magnitude of the final velocity for g1 + g2 was less than the magnitude of any initial velocity. as mass increased, what happened to the velocity? the velocity decreased. the velocity increased. the velocity of g1 + g2 could not be measured. the velocity was not affected by the mass increase.

Observations show that interstellar clouds can have almost any shape and