You testify as an expert witness in a case involving an accident in which car $A$ slid into the rear of car $B$, which was stopped at a red light along a road headed down a hill (Fig. 6-25). You find that the slope of the hill is $\theta=12.0^{\circ}$, that the cars were separated by distance $d=24.0 \mathrm{~m}$ when the driver of car $A$ put the car into a slide (it lacked any automatic anti-brake-lock system), and that the speed of car $A$ at the onset of braking was $v_{0}=18.0 \mathrm{~m} / \mathrm{s}$. With what speed did car $A$ hit car $B$ if the coefficient of kinetic friction was (a) $0.60$ (dry road surface) and (b) $0.10$ (road surface covered with wet leaves)?
Added by Robert S.
Step 1
0^\circ$, $\mu_k = 0.60$, $g = 9.81 \, \text{m/s}^2$ $a = (9.81 \, \text{m/s}^2) \sin(12.0^\circ) - (0.60)(9.81 \, \text{m/s}^2) \cos(12.0^\circ)$ $a \approx 3.72 \, \text{m/s}^2$ Show more…
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You testify as an expert witness in a case involving an accident in which car $A$ slid into the rear of car $B$, which was stopped at a red light along a road headed down a hill (Fig. $6-25$). You find that the slope of the hill is $\theta=12.0^{\circ}$, that the cars were separated by distance $d=24.0 \mathrm{~m}$ when the driver of car $A$ put the car into a slide (it lacked any automatic anti-brake-lock system), and that the speed of car $A$ at the onset of braking was $v_{0}=18.0 \mathrm{~m} / \mathrm{s}$. With what speed did car $A$ hit car $B$ if the coefficient of kinetic friction was (a) $0.60$ (dry road surface) and (b) $0.10$ (road surface covered with wet leaves)?
Jose C.
$\bullet$$\bullet$ Accident analysis. You have been called to testify as an expert witness in a trial involving an automobile accident. The speed limit on the highway where the accident occurred was 40 mph. The driver of the car slammed on his brakes, locking his wheels, and left skid marks as the car skidded to a halt. You measure the length of these skid marks to be $219 \mathrm{ft}, 9$ in. and determine that the coefficient of kinetic friction between the wheels and the pavement at the time of the accident was $0.40 .$ How fast was this car traveling (to the nearest number of mph) just before the driver hit his brakes? Was he guilty of speeding?
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