This would be called the "Escape Velocity "
Correct answer choice is:
D. A frequency higher than the original frequency.
Explanation:
This is a true case of Doppler's effect. The Doppler effect can be defined as the effect originated by a traveling source of waves in which there is a visible higher variation in pulse for observers towards what the source is progressing and a visible descending shift in rate for observers from what the source is dropping.
Let u = the speed of the car at the instant when braking begins.
The braking distance is s = 62.3 m, the acceleration is a = -5.9 m/s², and the braking duration is t = 4.15 s.
Use the formula s = ut + (1/2)at² to obtain
(u m/s)*(4.15 s) + 0.5*(-5.9 m/s²)*(4.5 s)² = (62.3 m)
4.15u = 62.3 + 50.8064 = 113.1064
u = 27.2546 m/s
Let v m/s be the speed with which the car strikes the tree.
Then
v = 27.2546 - 5.9*4.15
= 2.7696 m/s
Answer: 2.77 m/s (nearest hundredth)
