The Doppler effect is an effect produced by a moving source of sound or electromagnetic waves due to the relative motion of a source or a receiver. If an emergency vehicle approaches Bob and moves away from Jill, how does the frequency of the siren change?

the one on the bottom left

step-by-step explanation:

all of the other ones have a specific pattern

by definition, an arc subtended by a central angle of some given measure has the same measure. so .

pakistan's principal natural resources are arable land and water. about 25% of pakistan's agriculture accounts for about 21% [1] of gdp and employs about 43% of the labour force. in pakistan, the most agricultural province is punjab where wheat and cotton are the most grown.