Explanation:
A wavefront is the long edge that moves, for example, the crest or the trough. Each point on the wavefront emits a semicircular wave that moves at the propagation speed v. These are drawn at a time t later, so that they have moved a distance s = vt.
Answer:
1911
Explanation:
"In 1911, he was the first to discover that atoms have a small charged nucleus surrounded by largely empty space, and are circled by tiny electrons, which became known as the Rutherford model (or planetary model) of the atom."
Answer:
(a) angle record will be 46°
Explanation:
We have given speed = 33 rpm
Time t = 0.23 sec
We know that 1 revolution = 360°
And 1 minute = 60 sec
So 33 revolution/minute 
So angle record by vinyl 
, which is nearly equal to 46
So angle record by vinyl is 46°
So option (a) will be the correct answer
I think it’s maybe 2. But I’m not sure
D, spinal cord.
Please note that I am not 100% sure... Just taking an educated guess.
