Answer:
I believe the answer is D
Explanation: The doppler affect isan increase or decrease in the frequency of sound, light, or other waves as the source and observer move toward or away from each other.
Explanation:
It is given that,
= -40 mi/h,
= -40 mi/h
The negative sign indicates that x and y are decreasing.
We have to find
. Equation for the given variables according to the Pythagoras theorem is as follows.

Now, we will differentiate each side w.r.t 't' as follows.

or, 
So, when x = 4 mi, and y = 3 mi then z = 5 mi.
As, 
= 
= 
= 52
Thus, we can conclude that the cars are approaching at a rate of 52 mi/h.
Answer: The velocity at different marked time points are given as
t1 = -
t2 = +
t3 = +
t4 = -
t5 = 0
Explanation:
The slope of the tangent of the curve indicates the instantaneous velocity. So if the slope of the tangent is positive, that Is, the tangent makes a positive angle (above the horizontal axis) with the horizontal
axis, then the velocity at this point is positive, and if the slope of the tangent is negative, that is the tangent makes a negative angle with the horizontal axis (below the horizontal axis), then the velocity at this point is negative.
When the tangent of the line is parallel to the horizontal axis, the velocity is 0.
From the position-time graph attached, the sign on the instantaneous velocity for each time marked on the graph is given below
t1 = -
t2 = +
t3 = +
t4 = -
t5 = 0
QED!
Answer:
hope this helps i think the answer is C