As you drive down the road, you see and hear an ambulance go by you in the
opposite direction. after it passes, how is the frequency you hear different
from that being produced by the ambulance?
o
a. it is higher due to the doppler effect.
b. it is lower due to the doppler effect.
o
c. it has not changed, as the two vehicles cancel each othe_out.
o
d. it depends on which vehicle is moving the fastest.

B. It is lower due to the Doppler effect.

Explanation:

According to the Doppler effect, observed frequencies are higher than the source frequency if the source is moving towards the observer, and lower if the source is moving away from the observer.

After the ambulance passes, it is moving away from you, so the frequency you hear is lower than the frequency at the ambulance.

f=ma newton's second law 7x8=56n

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.