The second one, air is a poor conductor. If it weren't it wouldn't be used as such in construction. It's not the best insulator, but is quite efficient, and much cheaper to include a layer of air inside a wall than to add additional layers of asbestos :)
Answer:(A-P,S;B-P,S;C-Q,S;D-P,S)
Solution
(A)→P,S,(B)→P,S,(C)→Q,S,(D)→P,S.
Explanation:
That waves travel faster than the wave lenght!
Answer:
No. Because it would correspond to zero Instantaneous acceleration.
Explanation:
hope this helps